18160054724

Committed 01 Oct 2025 11:02AM UTC coverage: 77.214% (-1.4%) from 78.59%

Build # 18160054724

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Pull #8

github

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web-flow

Commit Message

Merge ac7783dac into d2f7274a0

Pull Request Pull Request #8: Cholesky branch: clip penalty eigenspectrum and add whitening latents

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66.28

/src/log_psplines/plotting/diagnostics.py

import os
from dataclasses import dataclass
from functools import wraps
from typing import Callable, Optional

import arviz as az
import matplotlib.pyplot as plt
import numpy as np


@dataclass
class DiagnosticsConfig:
    figsize: tuple = (12, 8)
    dpi: int = 150
    ess_threshold: int = 400
    rhat_threshold: float = 1.01


def safe_plot(filename: str, dpi: int = 150):
    """Decorator for safe plotting with error handling."""

    def decorator(plot_func: Callable):
        @wraps(plot_func)
        def wrapper(*args, **kwargs):
            try:
                result = plot_func(*args, **kwargs)
                plt.savefig(filename, dpi=dpi, bbox_inches="tight")
                plt.close()
                return True
            except Exception as e:
                print(
                    f"Warning: Failed to create {os.path.basename(filename)}: {e}"
                )
                plt.close("all")
                return False

        return wrapper

    return decorator


def plot_trace(idata: az.InferenceData, compact=True) -> plt.Figure:
    groups = {
        "delta": [
            v for v in idata.posterior.data_vars if v.startswith("delta")
        ],
        "phi": [v for v in idata.posterior.data_vars if v.startswith("phi")],
        "weights": [
            v for v in idata.posterior.data_vars if v.startswith("weights")
        ],
    }

    if compact:
        nrows = 3
    else:
        nrows = len(groups)
    fig, axes = plt.subplots(nrows, 2, figsize=(7, 3 * nrows))

    for row, (group_name, vars) in enumerate(groups.items()):

        # if vars are more than 1, and compact, then we need to repeat the axes
        if compact:
            group_axes = axes[row, :].reshape(1, 2)
            group_axes = np.repeat(group_axes, len(vars), axis=0)
        else:
            group_axes = axes[row, :]

        group_axes[0, 0].set_title(
            f"{group_name.capitalize()} Parameters", fontsize=14
        )

        for i, var in enumerate(vars):
            data = idata.posterior[
                var
            ].values  # shape is (nchain, nsamples, ndim) if ndim>1 else (nchain, nsamples)
            if data.ndim == 3:
                data = data[0].T  # shape is now (ndim, nsamples)

            ax_trace = group_axes[i, 0] if compact else group_axes[0]
            ax_hist = group_axes[i, 1] if compact else group_axes[1]
            ax_trace.set_ylabel(group_name, fontsize=8)
            ax_trace.set_xlabel("MCMC Step", fontsize=8)
            ax_hist.set_xlabel(group_name, fontsize=8)
            # place ylabel on right side of hist
            ax_hist.yaxis.set_label_position("right")
            ax_hist.set_ylabel("Density", fontsize=8, rotation=270, labelpad=0)

            # remove axes yspine for hist
            ax_hist.spines["left"].set_visible(False)
            ax_hist.spines["right"].set_visible(False)
            ax_hist.spines["top"].set_visible(False)
            ax_hist.set_yticks([])  # remove y ticks
            ax_hist.yaxis.set_ticks_position("none")

            ax_trace.spines["right"].set_visible(False)
            ax_trace.spines["top"].set_visible(False)

            color = f"C{i}"
            label = f"{var}"
            if group_name in ["phi", "delta"]:
                ax_trace.set_yscale("log")
                ax_hist.set_xscale("log")

            for p in data:
                ax_trace.plot(p, color=color, alpha=0.7, label=label)

                # if phi or delta, use log scale for hist-x, log for trace y
                if group_name in ["phi", "delta"]:
                    bins = np.logspace(
                        np.log10(np.min(p)), np.log10(np.max(p)), 30
                    )
                    logp = np.log(p)
                    log_grid, log_pdf = az.kde(logp)
                    grid = np.exp(log_grid)
                    pdf = log_pdf / grid  # change of variables
                else:
                    bins = 30
                    grid, pdf = az.kde(p)
                ax_hist.plot(grid, pdf, color=color, label=label)
                ax_hist.hist(
                    p, bins=bins, density=True, color=color, alpha=0.3
                )

                # KDE plot instead of histogram

    plt.suptitle("Parameter Traces", fontsize=16)
    plt.tight_layout()
    return fig


def plot_diagnostics(
    idata: az.InferenceData,
    outdir: str,
    n_channels: Optional[int] = None,
    n_freq: Optional[int] = None,
    runtime: Optional[float] = None,
    config: Optional[DiagnosticsConfig] = None,
) -> None:
    """
    Create essential MCMC diagnostics in organized subdirectories.
    """
    if outdir is None:
        return

    if config is None:
        config = DiagnosticsConfig()

    # Create diagnostics subdirectory
    diag_dir = os.path.join(outdir, "diagnostics")
    os.makedirs(diag_dir, exist_ok=True)

    print("Generating MCMC diagnostics...")

    # Generate summary report
    generate_diagnostics_summary(idata, diag_dir)

    # Essential diagnostics only
    _create_essential_diagnostics(
        idata, diag_dir, config, n_channels, n_freq, runtime
    )

    print(f"Diagnostics saved to {diag_dir}/")


def _create_essential_diagnostics(
    idata, diag_dir, config, n_channels, n_freq, runtime
):
    """Create only the essential diagnostic plots."""

    # 1. ArviZ trace plots
    @safe_plot(f"{diag_dir}/trace_plots.png", config.dpi)
    def create_trace_plots():
        return plot_trace(idata)

    create_trace_plots()

    # 2. Summary dashboard with key convergence metrics
    @safe_plot(f"{diag_dir}/summary_dashboard.png", config.dpi)
    def plot_summary():
        _plot_summary_dashboard(idata, config, n_channels, n_freq, runtime)

    plot_summary()

    # 3. Log posterior diagnostics
    @safe_plot(f"{diag_dir}/log_posterior.png", config.dpi)
    def plot_lp():
        _plot_log_posterior(idata, config)

    plot_lp()

    # 4. Acceptance rate diagnostics
    @safe_plot(f"{diag_dir}/acceptance_diagnostics.png", config.dpi)
    def plot_acceptance():
        _plot_acceptance_diagnostics(idata, config)

    plot_acceptance()

    # 5. Sampler-specific diagnostics
    _create_sampler_diagnostics(idata, diag_dir, config)

    # 6. Divergences diagnostics (for NUTS only)
    _create_divergences_diagnostics(idata, diag_dir, config)


def _plot_summary_dashboard(idata, config, n_channels, n_freq, runtime):
    """Essential summary dashboard."""

    # Check if R-hat is available
    rhat_available = False
    try:
        rhat = az.rhat(idata).to_array().values.flatten()
        rhat_values = rhat[~np.isnan(rhat)]
        rhat_available = len(rhat_values) > 0
    except Exception:
        pass

    # Create subplot layout based on data availability
    if rhat_available:
        # Full 2x3 layout when R-hat is available
        fig, axes = plt.subplots(2, 3, figsize=config.figsize)
        rhat_ax = axes[0, 1]
        scatter_ax = axes[0, 2]
        meta_ax = axes[1, 0]
        param_ax = axes[1, 1]
        status_ax = axes[1, 2]
    else:
        # Reduced 2x2 layout when R-hat is not available
        fig, axes = plt.subplots(
            2, 2, figsize=(config.figsize[0] * 0.8, config.figsize[1])
        )
        # Rearrange axes for 2x2 layout
        meta_ax = axes[0, 0]
        param_ax = axes[0, 1]
        status_ax = axes[1, 0]
        # Use bottom-right for additional info or leave empty
        axes[1, 1].axis("off")  # Hide unused subplot

    # ESS histogram (always in top-left)
    try:
        ess = az.ess(idata).to_array().values.flatten()
        ess_values = ess[~np.isnan(ess)]

        if len(ess_values) > 0:
            # Add color zones for ESS quality
            ess_thresholds = [
                (400, "red", "--", "Minimum reliable ESS"),
                (1000, "orange", "--", "Good ESS"),
                (
                    np.max(ess_values),
                    "green",
                    ":",
                    f"Max ESS = {np.max(ess_values):.0f}",
                ),
            ]

            ax_ess = axes[0, 0]  # Always available
            n, bins, patches = ax_ess.hist(
                ess_values, bins=30, alpha=0.7, edgecolor="black"
            )

            # Add reference lines
            for threshold, color, style, label in ess_thresholds:
                ax_ess.axvline(
                    x=threshold,
                    color=color,
                    linestyle=style,
                    linewidth=2 if threshold < np.max(ess_values) else 1,
                    alpha=0.8,
                    label=label,
                )

            ax_ess.set_xlabel("ESS")
            ax_ess.set_ylabel("Count")
            ax_ess.set_title("ESS Distribution")
            ax_ess.legend(loc="upper right", fontsize="x-small")
            ax_ess.grid(True, alpha=0.3)

            pct_good = (ess_values >= config.ess_threshold).mean() * 100
            ax_ess.text(
                0.02,
                0.98,
                f"Min: {ess_values.min():.0f}\nMean: {ess_values.mean():.0f}\n≥{config.ess_threshold}: {pct_good:.1f}%",
                transform=ax_ess.transAxes,
                fontsize=10,
                verticalalignment="top",
                bbox=dict(boxstyle="round", facecolor="lightblue", alpha=0.7),
            )
    except Exception:
        axes[0, 0].text(0.5, 0.5, "ESS unavailable", ha="center", va="center")
        axes[0, 0].set_title("ESS Distribution")

    # R-hat histogram and scatter (only when R-hat is available)
    if rhat_available and "rhat_ax" in locals():
        # Add shaded regions for R-hat quality
        rhat_ax.axvspan(
            1.0,
            config.rhat_threshold,
            alpha=0.1,
            color="green",
            label="Converged (≤1.01)",
        )
        rhat_ax.axvspan(
            config.rhat_threshold,
            1.1,
            alpha=0.1,
            color="yellow",
            label="Concerning (1.01-1.10)",
        )
        rhat_ax.axvspan(
            1.1,
            rhat_values.max(),
            alpha=0.1,
            color="red",
            label="Not converged (>1.10)",
        )

        rhat_ax.hist(rhat_values, bins=30, alpha=0.7, edgecolor="black")
        rhat_ax.axvline(
            1.0,
            color="green",
            linestyle="--",
            linewidth=2,
            label="Perfectly mixed",
        )
        rhat_ax.axvline(
            config.rhat_threshold,
            color="orange",
            linestyle="--",
            linewidth=2,
            label="Acceptable",
        )
        rhat_ax.set_xlabel("R-hat")
        rhat_ax.set_ylabel("Count")
        rhat_ax.set_title("R-hat Distribution")
        rhat_ax.legend(loc="upper right", fontsize="x-small")
        rhat_ax.grid(True, alpha=0.3)

        pct_excellent = (rhat_values <= 1.01).mean() * 100
        pct_concerning = (
            (rhat_values > 1.01) & (rhat_values <= 1.1)
        ).mean() * 100
        pct_bad = (rhat_values > 1.1).mean() * 100
        rhat_ax.text(
            0.02,
            0.98,
            f"Max: {rhat_values.max():.3f}\nMean: {rhat_values.mean():.3f}\n≤1.01: {pct_excellent:.1f}%\n>1.10: {pct_bad:.1f}%",
            transform=rhat_ax.transAxes,
            fontsize=9,
            verticalalignment="top",
            bbox=dict(boxstyle="round", facecolor="lightgreen", alpha=0.7),
        )

    # ESS vs R-hat scatter (only when R-hat is available)
    if rhat_available and "scatter_ax" in locals():
        try:
            if len(ess_values) > 0 and len(rhat_values) > 0:
                ess_all = az.ess(idata).to_array().values.flatten()
                rhat_all = az.rhat(idata).to_array().values.flatten()
                valid_mask = ~(np.isnan(ess_all) | np.isnan(rhat_all))

                if np.sum(valid_mask) > 0:
                    scatter_ax.scatter(
                        rhat_all[valid_mask],
                        ess_all[valid_mask],
                        alpha=0.6,
                        s=20,
                    )
                    scatter_ax.axvline(
                        config.rhat_threshold,
                        color="red",
                        linestyle="--",
                        alpha=0.7,
                    )
                    scatter_ax.axhline(
                        config.ess_threshold,
                        color="orange",
                        linestyle="--",
                        alpha=0.7,
                    )
                    scatter_ax.set_xlabel("R-hat")
                    scatter_ax.set_ylabel("ESS")
                    scatter_ax.set_title("Convergence Overview")
                    scatter_ax.grid(True, alpha=0.3)
        except Exception:
            scatter_ax.text(
                0.5, 0.5, "Scatter unavailable", ha="center", va="center"
            )
            scatter_ax.set_title("Convergence Overview")

    # Analysis metadata
    try:
        n_samples = idata.posterior.sizes.get("draw", 0)
        n_chains = idata.posterior.sizes.get("chain", 1)
        n_params = len(list(idata.posterior.data_vars))
        sampler_type = idata.attrs["sampler_type"]

        metadata_lines = [
            f"Sampler: {sampler_type}",
            f"Samples: {n_samples} × {n_chains} chains",
            f"Parameters: {n_params}",
        ]
        if n_channels is not None:
            metadata_lines.append(f"Channels: {n_channels}")
        if n_freq is not None:
            metadata_lines.append(f"Frequencies: {n_freq}")
        if runtime is not None:
            metadata_lines.append(f"Runtime: {runtime:.2f}s")

        meta_ax.text(
            0.05,
            0.95,
            "\n".join(metadata_lines),
            transform=meta_ax.transAxes,
            fontsize=12,
            verticalalignment="top",
            fontfamily="monospace",
        )
        meta_ax.set_title("Analysis Summary")
        meta_ax.axis("off")
    except Exception:
        meta_ax.text(
            0.5, 0.5, "Metadata unavailable", ha="center", va="center"
        )
        meta_ax.set_title("Analysis Summary")
        meta_ax.axis("off")

    # Parameter counts (placeholder - turned off as not helpful per user feedback)
    try:
        # Just show a summary text instead of the full bar chart
        param_groups = _group_parameters_simple(idata)
        if param_groups:
            summary_text = "Parameter Summary:\n"
            for group_name, params in param_groups.items():
                if params:  # Only show non-empty groups
                    summary_text += f"{group_name}: {len(params)}\n"
            param_ax.text(
                0.05,
                0.95,
                summary_text.strip(),
                transform=param_ax.transAxes,
                fontsize=11,
                verticalalignment="top",
                fontfamily="monospace",
            )
        param_ax.set_title("Parameter Summary")
        param_ax.axis("off")  # Don't show axes for this simple text summary
    except Exception:
        param_ax.text(
            0.5,
            0.5,
            "Parameter summary\nunavailable",
            ha="center",
            va="center",
        )
        param_ax.set_title("Parameter Summary")
        param_ax.axis("off")

    # Convergence status
    try:
        ess_retrieved = []
        rhat_retrieved = []
        try:
            ess_retrieved = az.ess(idata).to_array().values.flatten()
            ess_retrieved = ess_retrieved[~np.isnan(ess_retrieved)]
        except:
            pass
        try:
            rhat_retrieved = az.rhat(idata).to_array().values.flatten()
            rhat_retrieved = rhat_retrieved[~np.isnan(rhat_retrieved)]
        except:
            pass

        status_lines = ["Convergence Status:"]

        if len(ess_retrieved) > 0:
            ess_good = (ess_retrieved >= config.ess_threshold).mean() * 100
            status_lines.append(
                f"ESS ≥ {config.ess_threshold}: {ess_good:.0f}%"
            )

        if len(rhat_retrieved) > 0:
            rhat_good = (rhat_retrieved <= config.rhat_threshold).mean() * 100
            status_lines.append(
                f"R-hat ≤ {config.rhat_threshold}: {rhat_good:.0f}%"
            )

        status_lines.append("")
        status_lines.append("Overall Status:")

        if len(ess_retrieved) > 0 and len(rhat_retrieved) > 0:
            if ess_good >= 90 and rhat_good >= 90:
                status_lines.append("✓ EXCELLENT")
                color = "green"
            elif ess_good >= 75 and rhat_good >= 75:
                status_lines.append("✓ GOOD")
                color = "orange"
            else:
                status_lines.append("⚠ NEEDS ATTENTION")
                color = "red"
        elif len(ess_retrieved) > 0:
            if ess_good >= 90:
                status_lines.append("✓ GOOD (based on ESS only)")
                color = "green"
            elif ess_good >= 75:
                status_lines.append("✓ ADEQUATE (based on ESS only)")
                color = "orange"
            else:
                status_lines.append("⚠ NEEDS ATTENTION")
                color = "red"
        else:
            status_lines.append("? UNABLE TO ASSESS")
            color = "gray"

        status_ax.text(
            0.05,
            0.95,
            "\n".join(status_lines),
            transform=status_ax.transAxes,
            fontsize=11,
            verticalalignment="top",
            fontfamily="monospace",
            color=color,
        )
        status_ax.set_title("Convergence Status")
        status_ax.axis("off")
    except Exception:
        status_ax.text(
            0.5, 0.5, "Status unavailable", ha="center", va="center"
        )
        status_ax.set_title("Convergence Status")
        status_ax.axis("off")

    plt.tight_layout()


def _plot_log_posterior(idata, config):
    """Log posterior diagnostics."""
    fig, axes = plt.subplots(2, 2, figsize=config.figsize)

    # Check for lp first, then log_likelihood
    if "lp" in idata.sample_stats:
        lp_values = idata.sample_stats["lp"].values.flatten()
        var_name = "lp"
        title_prefix = "Log Posterior"
    elif "log_likelihood" in idata.sample_stats:
        lp_values = idata.sample_stats["log_likelihood"].values.flatten()
        var_name = "log_likelihood"
        title_prefix = "Log Likelihood"
    else:
        # Create a fallback layout when no posterior data available
        fig, axes = plt.subplots(1, 1, figsize=config.figsize)
        axes.text(
            0.5,
            0.5,
            "No log posterior\nor log likelihood\navailable",
            ha="center",
            va="center",
            fontsize=14,
        )
        axes.set_title("Log Posterior Diagnostics")
        axes.axis("off")
        plt.tight_layout()
        return

    # Trace plot with running mean overlaid
    axes[0, 0].plot(
        lp_values, alpha=0.7, linewidth=1, color="blue", label="Trace"
    )

    # Add running mean on the same plot
    window_size = max(10, len(lp_values) // 100)
    if len(lp_values) > window_size:
        running_mean = np.convolve(
            lp_values, np.ones(window_size) / window_size, mode="valid"
        )
        axes[0, 0].plot(
            range(window_size // 2, window_size // 2 + len(running_mean)),
            running_mean,
            alpha=0.9,
            linewidth=3,
            color="red",
            label=f"Running mean (w={window_size})",
        )

    axes[0, 0].set_xlabel("Iteration")
    axes[0, 0].set_ylabel(title_prefix)
    axes[0, 0].set_title(f"{title_prefix} Trace with Running Mean")
    axes[0, 0].legend(loc="best", fontsize="small")
    axes[0, 0].grid(True, alpha=0.3)

    # Distribution
    axes[0, 1].hist(
        lp_values, bins=50, alpha=0.7, density=True, edgecolor="black"
    )
    axes[0, 1].axvline(
        np.mean(lp_values),
        color="red",
        linestyle="--",
        linewidth=2,
        label=f"Mean: {np.mean(lp_values):.1f}",
    )
    axes[0, 1].set_xlabel(title_prefix)
    axes[0, 1].set_ylabel("Density")
    axes[0, 1].set_title(f"{title_prefix} Distribution")
    axes[0, 1].legend(loc="best", fontsize="small")
    axes[0, 1].grid(True, alpha=0.3)

    # Step-to-step changes
    lp_diff = np.diff(lp_values)
    axes[1, 0].plot(lp_diff, alpha=0.5, linewidth=1)
    axes[1, 0].axhline(0, color="red", linestyle="--", alpha=0.7)
    axes[1, 0].axhline(
        np.mean(lp_diff),
        color="blue",
        linestyle="--",
        alpha=0.7,
        label=f"Mean change: {np.mean(lp_diff):.1f}",
    )
    axes[1, 0].set_xlabel("Iteration")
    axes[1, 0].set_ylabel(f"{title_prefix} Difference")
    axes[1, 0].set_title("Step-to-Step Changes")
    axes[1, 0].legend(loc="best", fontsize="small")
    axes[1, 0].grid(True, alpha=0.3)

    # Summary statistics
    stats_lines = [
        f"Mean: {np.mean(lp_values):.2f}",
        f"Std: {np.std(lp_values):.2f}",
        f"Min: {np.min(lp_values):.2f}",
        f"Max: {np.max(lp_values):.2f}",
        f"Range: {np.max(lp_values) - np.min(lp_values):.2f}",
        "",
        "Stability:",
        f"Final variation: {np.std(lp_values[-len(lp_values)//4:]):.2f}",
    ]

    axes[1, 1].text(
        0.05,
        0.95,
        "\n".join(stats_lines),
        transform=axes[1, 1].transAxes,
        fontsize=10,
        verticalalignment="top",
        fontfamily="monospace",
        bbox=dict(boxstyle="round", facecolor="lightblue", alpha=0.8),
    )
    axes[1, 1].set_title("Posterior Statistics")
    axes[1, 1].axis("off")

    plt.tight_layout()


def _plot_acceptance_diagnostics(idata, config):
    """Acceptance rate diagnostics."""
    accept_key = None
    if "accept_prob" in idata.sample_stats:
        accept_key = "accept_prob"
    elif "acceptance_rate" in idata.sample_stats:
        accept_key = "acceptance_rate"

    if accept_key is None:
        fig, ax = plt.subplots(figsize=config.figsize)
        ax.text(
            0.5,
            0.5,
            "Acceptance rate data unavailable",
            ha="center",
            va="center",
        )
        ax.set_title("Acceptance Rate Diagnostics")
        return

    fig, axes = plt.subplots(2, 2, figsize=config.figsize)

    accept_rates = idata.sample_stats[accept_key].values.flatten()
    target_rate = getattr(idata.attrs, "target_accept_rate", 0.44)
    sampler_type = (
        idata.attrs["sampler_type"].lower()
        if "sampler_type" in idata.attrs
        else "unknown"
    )
    sampler_type = "NUTS" if "nuts" in sampler_type else "MH"

    # Define good ranges based on sampler
    if target_rate > 0.5:  # NUTS
        good_range = (0.7, 0.9)
        low_range = (0.0, 0.6)
        high_range = (0.9, 1.0)
        concerning_range = (0.6, 0.7)
    else:  # MH
        good_range = (0.2, 0.5)
        low_range = (0.0, 0.2)
        high_range = (0.5, 1.0)
        concerning_range = (0.1, 0.2)  # MH can be lower than NUTS

    # Trace plot with color zones
    # Add background zones
    axes[0, 0].axhspan(
        good_range[0],
        good_range[1],
        alpha=0.1,
        color="green",
        label=f"Good ({good_range[0]:.1f}-{good_range[1]:.1f})",
    )
    axes[0, 0].axhspan(
        low_range[0], low_range[1], alpha=0.1, color="red", label="Too low"
    )
    axes[0, 0].axhspan(
        high_range[0],
        high_range[1],
        alpha=0.1,
        color="orange",
        label="Too high",
    )
    if concerning_range[1] > concerning_range[0]:
        axes[0, 0].axhspan(
            concerning_range[0],
            concerning_range[1],
            alpha=0.1,
            color="yellow",
            label="Concerning",
        )

    # Main trace plot
    axes[0, 0].plot(
        accept_rates, alpha=0.8, linewidth=1, color="blue", label="Trace"
    )
    axes[0, 0].axhline(
        target_rate,
        color="red",
        linestyle="--",
        linewidth=2,
        label=f"Target ({target_rate})",
    )

    # Add running average on the same plot
    window_size = max(10, len(accept_rates) // 50)
    if len(accept_rates) > window_size:
        running_mean = np.convolve(
            accept_rates, np.ones(window_size) / window_size, mode="valid"
        )
        axes[0, 0].plot(
            range(window_size // 2, window_size // 2 + len(running_mean)),
            running_mean,
            alpha=0.9,
            linewidth=3,
            color="purple",
            label=f"Running mean (w={window_size})",
        )

    axes[0, 0].set_xlabel("Iteration")
    axes[0, 0].set_ylabel("Acceptance Rate")
    axes[0, 0].set_title(f"{sampler_type} Acceptance Rate Trace")
    axes[0, 0].legend(loc="best", fontsize="small")
    axes[0, 0].grid(True, alpha=0.3)

    # Add interpretation text
    interpretation = f"{sampler_type} aims for {target_rate:.2f}."
    if target_rate > 0.5:
        interpretation += " Green: efficient sampling."
    else:
        interpretation += " MH adapts to find optimal rate."
    axes[0, 0].text(
        0.02,
        0.02,
        interpretation,
        transform=axes[0, 0].transAxes,
        fontsize=9,
        bbox=dict(boxstyle="round", facecolor="wheat", alpha=0.7),
    )

    # Distribution
    axes[0, 1].hist(
        accept_rates, bins=30, alpha=0.7, density=True, edgecolor="black"
    )
    axes[0, 1].axvline(
        target_rate,
        color="red",
        linestyle="--",
        linewidth=2,
        label=f"Target ({target_rate})",
    )
    axes[0, 1].set_xlabel("Acceptance Rate")
    axes[0, 1].set_ylabel("Density")
    axes[0, 1].set_title("Acceptance Rate Distribution")
    axes[0, 1].legend()
    axes[0, 1].grid(True, alpha=0.3)

    # Since running means are already overlaid on the main plot, use the bottom row for additional info

    # Additional acceptance analysis - evolution over time
    if len(accept_rates) > 10:
        # Show moving standard deviation or coefficient of variation
        window_std = np.array(
            [
                np.std(accept_rates[max(0, i - 20) : i + 1])
                for i in range(len(accept_rates))
            ]
        )
        axes[1, 0].plot(window_std, alpha=0.7, color="green")
        axes[1, 0].set_xlabel("Iteration")
        axes[1, 0].set_ylabel("Rolling Std")
        axes[1, 0].set_title("Rolling Standard Deviation")
        axes[1, 0].grid(True, alpha=0.3)
    else:
        axes[1, 0].text(
            0.5,
            0.5,
            "Acceptance variability\nanalysis unavailable",
            ha="center",
            va="center",
        )
        axes[1, 0].set_title("Acceptance Stability")

    # Summary statistics (expanded)
    stats_text = [
        f"Sampler: {sampler_type}",
        f"Target: {target_rate:.3f}",
        f"Mean: {np.mean(accept_rates):.3f}",
        f"Std: {np.std(accept_rates):.3f}",
        f"CV: {np.std(accept_rates)/np.mean(accept_rates):.3f}",
        f"Min: {np.min(accept_rates):.3f}",
        f"Max: {np.max(accept_rates):.3f}",
        "",
        "Stability:",
        f"Final std: {np.std(accept_rates[-len(accept_rates)//4:]):.3f}",
    ]

    axes[1, 1].text(
        0.05,
        0.95,
        "\n".join(stats_text),
        transform=axes[1, 1].transAxes,
        fontsize=9,
        verticalalignment="top",
        fontfamily="monospace",
    )
    axes[1, 1].set_title("Acceptance Analysis")
    axes[1, 1].axis("off")

    plt.tight_layout()


def _create_sampler_diagnostics(idata, diag_dir, config):
    """Create sampler-specific diagnostics."""

    # Better sampler detection - check sampler type first
    sampler_type = (
        idata.attrs["sampler_type"].lower()
        if "sampler_type" in idata.attrs
        else "unknown"
    )

    # Check for NUTS-specific fields that MH definitely doesn't have
    nuts_specific_fields = [
        "energy",
        "num_steps",
        "tree_depth",
        "diverging",
        "energy_error",
    ]

    has_nuts = (
        any(field in idata.sample_stats for field in nuts_specific_fields)
        or "nuts" in sampler_type
    )

    # Check for MH-specific fields (exclude anything NUTS might have)
    has_mh = "step_size_mean" in idata.sample_stats and not has_nuts

    if has_nuts:

        @safe_plot(f"{diag_dir}/nuts_diagnostics.png", config.dpi)
        def plot_nuts():
            _plot_nuts_diagnostics(idata, config)

        plot_nuts()
    elif has_mh:

        @safe_plot(f"{diag_dir}/mh_step_sizes.png", config.dpi)
        def plot_mh():
            _plot_mh_step_sizes(idata, config)

        plot_mh()


def _plot_nuts_diagnostics(idata, config):
    """NUTS diagnostics with enhanced information."""
    # Determine available data to decide layout
    has_energy = "energy" in idata.sample_stats
    has_potential = "potential_energy" in idata.sample_stats
    has_steps = "num_steps" in idata.sample_stats
    has_accept = "accept_prob" in idata.sample_stats
    has_divergences = "diverging" in idata.sample_stats
    has_tree_depth = "tree_depth" in idata.sample_stats
    has_energy_error = "energy_error" in idata.sample_stats

    # Create a 2x2 layout, potentially combining energy and potential on same plot
    fig, axes = plt.subplots(2, 2, figsize=config.figsize)

    # Top-left: Energy diagnostics (combine Hamiltonian and Potential if both available)
    energy_ax = axes[0, 0]

    if has_energy and has_potential:
        # Both available - plot them together on one plot
        energy = idata.sample_stats.energy.values.flatten()
        potential = idata.sample_stats.potential_energy.values.flatten()

        # Plot both energies on same axis
        energy_ax.plot(
            energy, alpha=0.7, linewidth=1, color="blue", label="Hamiltonian"
        )
        energy_ax.plot(
            potential,
            alpha=0.7,
            linewidth=1,
            color="orange",
            label="Potential",
        )

        # Add difference (which relates to kinetic energy)
        energy_diff = energy - potential
        # Create second y-axis for difference
        ax2 = energy_ax.twinx()
        ax2.plot(
            energy_diff,
            alpha=0.5,
            linewidth=1,
            color="red",
            label="H - Potential (Kinetic)",
            linestyle="--",
        )
        ax2.set_ylabel("Energy Difference", color="red")
        ax2.tick_params(axis="y", labelcolor="red")

        energy_ax.set_xlabel("Iteration")
        energy_ax.set_ylabel("Energy", color="blue")
        energy_ax.tick_params(axis="y", labelcolor="blue")
        energy_ax.set_title("Hamiltonian & Potential Energy")
        energy_ax.legend(loc="best", fontsize="small")
        energy_ax.grid(True, alpha=0.3)

        # Add statistics
        energy_ax.text(
            0.02,
            0.98,
            f"H: μ={np.mean(energy):.1f}, σ={np.std(energy):.1f}\nP: μ={np.mean(potential):.1f}, σ={np.std(potential):.1f}",
            transform=energy_ax.transAxes,
            fontsize=8,
            bbox=dict(boxstyle="round", facecolor="lightblue", alpha=0.8),
            verticalalignment="top",
        )

    elif has_energy:
        # Only Hamiltonian energy
        energy = idata.sample_stats.energy.values.flatten()
        energy_ax.plot(energy, alpha=0.7, linewidth=1, color="blue")
        energy_ax.set_xlabel("Iteration")
        energy_ax.set_ylabel("Hamiltonian Energy")
        energy_ax.set_title("Hamiltonian Energy Trace")
        energy_ax.grid(True, alpha=0.3)

    elif has_potential:
        # Only potential energy
        potential = idata.sample_stats.potential_energy.values.flatten()
        energy_ax.plot(potential, alpha=0.7, linewidth=1, color="orange")
        energy_ax.set_xlabel("Iteration")
        energy_ax.set_ylabel("Potential Energy")
        energy_ax.set_title("Potential Energy Trace")
        energy_ax.grid(True, alpha=0.3)

    else:
        energy_ax.text(
            0.5,
            0.5,
            "Energy data\nunavailable",
            ha="center",
            va="center",
            transform=energy_ax.transAxes,
        )
        energy_ax.set_title("Energy Diagnostics")

    # Top-right: Sampling efficiency diagnostics
    if has_steps:
        steps_ax = axes[0, 1]
        num_steps = idata.sample_stats.num_steps.values.flatten()

        # Show histogram with color zones for step efficiency
        n, bins, edges = steps_ax.hist(
            num_steps, bins=20, alpha=0.7, edgecolor="black"
        )

        # Add shaded regions for different efficiency levels
        # Green: efficient (tree depth ≤5, ~32 steps)
        # Yellow: moderate (tree depth 6-8, ~64-256 steps)
        # Red: inefficient (tree depth >8, >256 steps)
        steps_ax.axvspan(
            0, 64, alpha=0.1, color="green", label="Efficient (≤64)"
        )
        steps_ax.axvspan(
            64, 256, alpha=0.1, color="yellow", label="Moderate (65-256)"
        )
        steps_ax.axvspan(
            256,
            np.max(num_steps),
            alpha=0.1,
            color="red",
            label="Inefficient (>256)",
        )

        # Add reference lines for different tree depths
        for depth in [5, 7, 10]:  # Common tree depths
            max_steps = 2**depth
            steps_ax.axvline(
                x=max_steps,
                color="gray",
                linestyle=":",
                alpha=0.7,
                linewidth=1,
                label=f"2^{depth} ({max_steps})",
            )

        steps_ax.set_xlabel("Leapfrog Steps")
        steps_ax.set_ylabel("Trajectories")
        steps_ax.set_title("Leapfrog Steps Distribution")
        steps_ax.legend(loc="best", fontsize="small")
        steps_ax.grid(True, alpha=0.3)

        # Add efficiency statistics
        pct_inefficient = (num_steps > 256).mean() * 100
        pct_moderate = ((num_steps > 64) & (num_steps <= 256)).mean() * 100
        pct_efficient = (num_steps <= 64).mean() * 100
        steps_ax.text(
            0.02,
            0.98,
            f"Efficient: {pct_efficient:.1f}%\nModerate: {pct_moderate:.1f}%\nInefficient: {pct_inefficient:.1f}%\nMean steps: {np.mean(num_steps):.1f}",
            transform=steps_ax.transAxes,
            fontsize=7,
            bbox=dict(boxstyle="round", facecolor="lightblue", alpha=0.8),
            verticalalignment="top",
        )

    else:
        axes[0, 1].text(
            0.5, 0.5, "Steps data\nunavailable", ha="center", va="center"
        )
        axes[0, 1].set_title("Sampling Steps")

    # Bottom-left: Acceptance and NS divergence diagnostics
    accept_ax = axes[1, 0]

    if has_accept:
        accept_prob = idata.sample_stats.accept_prob.values.flatten()

        # Plot acceptance probability with guidance zones
        accept_ax.fill_between(
            range(len(accept_prob)),
            0.7,
            0.9,
            alpha=0.1,
            color="green",
            label="Good (0.7-0.9)",
        )
        accept_ax.fill_between(
            range(len(accept_prob)),
            0,
            0.6,
            alpha=0.1,
            color="red",
            label="Too low",
        )
        accept_ax.fill_between(
            range(len(accept_prob)),
            0.9,
            1.0,
            alpha=0.1,
            color="orange",
            label="Too high",
        )

        accept_ax.plot(
            accept_prob,
            alpha=0.8,
            linewidth=1,
            color="blue",
            label="Acceptance prob",
        )
        accept_ax.axhline(
            0.8,
            color="red",
            linestyle="--",
            linewidth=2,
            label="NUTS target (0.8)",
        )
        accept_ax.set_xlabel("Iteration")
        accept_ax.set_ylabel("Acceptance Probability")
        accept_ax.set_title("NUTS Acceptance Diagnostic")
        accept_ax.legend(loc="best", fontsize="small")
        accept_ax.set_ylim(0, 1)
        accept_ax.grid(True, alpha=0.3)

    else:
        accept_ax.text(
            0.5, 0.5, "Acceptance data\nunavailable", ha="center", va="center"
        )
        accept_ax.set_title("Acceptance Diagnostic")

    # Bottom-right: Summary statistics and additional diagnostics
    summary_ax = axes[1, 1]

    # Collect available statistics
    stats_lines = []

    if has_energy:
        energy = idata.sample_stats.energy.values.flatten()
        stats_lines.append(
            f"Energy: μ={np.mean(energy):.1f}, σ={np.std(energy):.1f}"
        )

    if has_potential:
        potential = idata.sample_stats.potential_energy.values.flatten()
        stats_lines.append(
            f"Potential: μ={np.mean(potential):.1f}, σ={np.std(potential):.1f}"
        )

    if has_steps:
        num_steps = idata.sample_stats.num_steps.values.flatten()
        stats_lines.append(
            f"Steps: μ={np.mean(num_steps):.1f}, max={np.max(num_steps):.0f}"
        )
        stats_lines.append("")

    if has_tree_depth:
        tree_depth = idata.sample_stats.tree_depth.values.flatten()
        stats_lines.append(f"Tree depth: μ={np.mean(tree_depth):.1f}")
        pct_max_depth = (tree_depth >= 10).mean() * 100
        stats_lines.append(f"Max depth (≥10): {pct_max_depth:.1f}%")

    if has_divergences:
        divergences = idata.sample_stats.diverging.values.flatten()
        n_divergences = np.sum(divergences)
        pct_divergent = n_divergences / len(divergences) * 100
        stats_lines.append(
            f"Divergent: {n_divergences}/{len(divergences)} ({pct_divergent:.2f}%)"
        )

    if has_energy_error:
        energy_error = idata.sample_stats.energy_error.values.flatten()
        stats_lines.append(
            f"Energy error: |μ|={np.mean(np.abs(energy_error)):.3f}"
        )

    if not stats_lines:
        summary_ax.text(
            0.5,
            0.5,
            "No diagnostics\ndata available",
            ha="center",
            va="center",
            transform=summary_ax.transAxes,
        )
        summary_ax.set_title("NUTS Statistics")
        summary_ax.axis("off")
    else:
        summary_text = "\n".join(["NUTS Diagnostics:"] + [""] + stats_lines)
        summary_ax.text(
            0.05,
            0.95,
            summary_text,
            transform=summary_ax.transAxes,
            fontsize=10,
            verticalalignment="top",
            fontfamily="monospace",
            bbox=dict(boxstyle="round", facecolor="wheat", alpha=0.9),
        )
        summary_ax.set_title("NUTS Summary Statistics")
        summary_ax.axis("off")

    plt.tight_layout()


def _plot_mh_step_sizes(idata, config):
    """MH step size diagnostics."""
    fig, axes = plt.subplots(2, 2, figsize=config.figsize)

    step_means = idata.sample_stats.step_size_mean.values.flatten()
    step_stds = idata.sample_stats.step_size_std.values.flatten()

    # Step size evolution
    axes[0, 0].plot(
        step_means, alpha=0.7, linewidth=1, label="Mean", color="blue"
    )
    axes[0, 0].plot(
        step_stds, alpha=0.7, linewidth=1, label="Std", color="orange"
    )
    axes[0, 0].set_xlabel("Iteration")
    axes[0, 0].set_ylabel("Step Size")
    axes[0, 0].set_title("Step Size Evolution")
    axes[0, 0].legend()
    axes[0, 0].grid(True, alpha=0.3)

    # Step size distributions
    axes[0, 1].hist(step_means, bins=30, alpha=0.5, label="Mean", color="blue")
    axes[0, 1].hist(step_stds, bins=30, alpha=0.5, label="Std", color="orange")
    axes[0, 1].set_xlabel("Step Size")
    axes[0, 1].set_ylabel("Count")
    axes[0, 1].set_title("Step Size Distributions")
    axes[0, 1].legend()
    axes[0, 1].grid(True, alpha=0.3)

    # Step size adaptation quality
    axes[1, 0].plot(step_means / step_stds, alpha=0.7, linewidth=1)
    axes[1, 0].set_xlabel("Iteration")
    axes[1, 0].set_ylabel("Mean / Std")
    axes[1, 0].set_title("Step Size Consistency")
    axes[1, 0].grid(True, alpha=0.3)

    # Summary statistics
    summary_lines = [
        "Step Size Summary:",
        f"Final mean: {step_means[-1]:.4f}",
        f"Final std: {step_stds[-1]:.4f}",
        f"Mean of means: {np.mean(step_means):.4f}",
        f"Mean of stds: {np.mean(step_stds):.4f}",
        "",
        "Adaptation Quality:",
        f"CV of means: {np.std(step_means)/np.mean(step_means):.3f}",
        f"CV of stds: {np.std(step_stds)/np.mean(step_stds):.3f}",
    ]

    axes[1, 1].text(
        0.05,
        0.95,
        "\n".join(summary_lines),
        transform=axes[1, 1].transAxes,
        fontsize=10,
        verticalalignment="top",
        fontfamily="monospace",
    )
    axes[1, 1].set_title("Step Size Statistics")
    axes[1, 1].axis("off")

    plt.tight_layout()


def _create_divergences_diagnostics(idata, diag_dir, config):
    """Create divergences diagnostics for NUTS samplers."""
    # Check if divergences data exists
    has_divergences = "diverging" in idata.sample_stats
    has_channel_divergences = any(
        key.startswith("diverging_channel_") for key in idata.sample_stats
    )

    if not has_divergences and not has_channel_divergences:
        return  # Nothing to plot

    @safe_plot(f"{diag_dir}/divergences.png", config.dpi)
    def plot_divergences():
        _plot_divergences(idata, config)

    plot_divergences()


def _plot_divergences(idata, config):
    """Plot divergences diagnostics."""
    # Collect all divergence data
    divergences_data = {}

    # Check for main divergences (single chain NUTS)
    if "diverging" in idata.sample_stats:
        divergences_data["main"] = (
            idata.sample_stats.diverging.values.flatten()
        )

    # Check for channel-specific divergences (blocked NUTS)
    channel_divergences = {}
    for key in idata.sample_stats:
        if key.startswith("diverging_channel_"):
            channel_idx = key.replace("diverging_channel_", "")
            channel_divergences[int(channel_idx)] = idata.sample_stats[
                key
            ].values.flatten()

    if channel_divergences:
        divergences_data.update(channel_divergences)

    if not divergences_data:
        fig, ax = plt.subplots(figsize=config.figsize)
        ax.text(
            0.5, 0.5, "No divergence data available", ha="center", va="center"
        )
        ax.set_title("Divergences Diagnostics")
        return

    # Create subplot layout
    n_plots = len(divergences_data)
    if n_plots == 1:
        fig, axes = plt.subplots(1, 2, figsize=config.figsize)
        trace_ax, summary_ax = axes
    else:
        # Multiple plots - arrange in grid
        cols = 2
        rows = (n_plots + 1) // cols  # Ceiling division
        fig, axes = plt.subplots(rows, cols, figsize=config.figsize)
        if rows == 1:
            axes = axes.reshape(1, -1)
        axes = axes.flatten()

        # Last plot goes in summary_ax if odd number
        if n_plots % 2 == 1:
            trace_axes = axes[:-1]
            summary_ax = axes[-1]
        else:
            trace_axes = axes
            summary_ax = None

    # Plot divergences traces
    total_divergences = 0
    total_iterations = 0

    plot_idx = 0
    for label, div_values in divergences_data.items():
        if label == "main":
            title = "NUTS Divergences"
            ax = trace_axes[plot_idx] if n_plots > 1 else axes[0]
        else:
            title = f"Channel {label} Divergences"
            ax = trace_axes[plot_idx] if n_plots > 1 else axes[0]
            plot_idx += 1

        # Plot divergence indicators (where divergences occur)
        div_indices = np.where(div_values)[0]
        ax.scatter(
            div_indices,
            np.ones_like(div_indices),
            color="red",
            marker="x",
            s=50,
            linewidth=2,
            label="Divergent",
            alpha=0.8,
        )

        # Add background shading for divergent regions
        if len(div_indices) > 0:
            for idx in div_indices:
                ax.axvspan(idx - 0.5, idx + 0.5, alpha=0.2, color="red")

        ax.set_xlabel("Iteration")
        ax.set_ylabel("Divergence Indicator")
        ax.set_title(title)
        ax.set_yticks([0, 1])
        ax.set_yticklabels(["No", "Yes"])
        ax.grid(True, alpha=0.3)

        # Add statistics
        n_divergent = np.sum(div_values)
        pct_divergent = n_divergent / len(div_values) * 100
        stats_text = f"{n_divergent}/{len(div_values)} ({pct_divergent:.2f}%)"
        ax.text(
            0.02,
            0.98,
            stats_text,
            transform=ax.transAxes,
            fontsize=10,
            bbox=dict(boxstyle="round", facecolor="lightcoral", alpha=0.8),
            verticalalignment="top",
        )

        total_divergences += n_divergent
        total_iterations += len(div_values)

        # Legend only if there are divergences
        if n_divergent > 0:
            ax.legend(loc="upper right", fontsize="small")

    # Summary plot
    if summary_ax is not None and n_plots > 1:
        summary_ax.text(
            0.05,
            0.95,
            _get_divergences_summary(divergences_data),
            transform=summary_ax.transAxes,
            fontsize=12,
            verticalalignment="top",
            fontfamily="monospace",
            bbox=dict(boxstyle="round", facecolor="wheat", alpha=0.9),
        )
        summary_ax.set_title("Divergences Summary")
        summary_ax.axis("off")
    elif n_plots == 1:
        axes[1].text(
            0.05,
            0.95,
            _get_divergences_summary(divergences_data),
            transform=axes[1].transAxes,
            fontsize=12,
            verticalalignment="top",
            fontfamily="monospace",
            bbox=dict(boxstyle="round", facecolor="wheat", alpha=0.9),
        )
        axes[1].set_title("Divergences Summary")
        axes[1].axis("off")

    # Overall title
    overall_pct = (
        total_divergences / total_iterations * 100
        if total_iterations > 0
        else 0
    )
    fig.suptitle(f"Overall Divergences: {overall_pct:.2f}%")

    plt.tight_layout()


def _get_divergences_summary(divergences_data):
    """Generate text summary of divergences."""
    lines = ["Divergences Summary:", ""]

    total_divergences = 0
    total_iterations = 0

    for label, div_values in divergences_data.items():
        n_divergent = np.sum(div_values)
        pct_divergent = n_divergent / len(div_values) * 100

        if label == "main":
            lines.append(
                f"NUTS: {n_divergent}/{len(div_values)} ({pct_divergent:.2f}%)"
            )
        else:
            lines.append(
                f"Channel {label}: {n_divergent}/{len(div_values)} ({pct_divergent:.2f}%)"
            )

        total_divergences += n_divergent
        total_iterations += len(div_values)

    lines.append("")
    overall_pct = (
        total_divergences / total_iterations * 100
        if total_iterations > 0
        else 0
    )
    lines.append(
        f"Total: {total_divergences}/{total_iterations} ({overall_pct:.2f}%)"
    )

    lines.append("")
    lines.append("Interpretation:")
    if overall_pct == 0:
        lines.append("  ✓ No divergences detected")
        lines.append("    Sampling appears well-behaved")
    elif overall_pct < 0.1:
        lines.append("  ~ Few divergences")
        lines.append("    Generally good, but monitor")
    elif overall_pct < 1.0:
        lines.append("  ⚠ Some divergences detected")
        lines.append("    May indicate sampling issues")
    else:
        lines.append("  ✗ Many divergences!")
        lines.append("    Significant sampling problems")
        lines.append("    Consider model reparameterization")

    return "\n".join(lines)


def _plot_grouped_traces(idata, figsize):
    """Create grouped trace plots for delta, phi, and weights parameters."""
    # Define color cycle for multiple parameters in each group
    colors = [
        "blue",
        "red",
        "green",
        "orange",
        "purple",
        "brown",
        "pink",
        "gray",
        "olive",
        "cyan",
    ]

    # Group parameters by type
    delta_params = [
        param
        for param in idata.posterior.data_vars
        if param.startswith("delta")
    ]
    phi_params = [
        param for param in idata.posterior.data_vars if param.startswith("phi")
    ]
    weights_params = [
        param
        for param in idata.posterior.data_vars
        if param.startswith("weights")
    ]

    # Create 3 subplots
    fig, axes = plt.subplots(3, 1, figsize=figsize)

    # Plot delta parameters
    ax = axes[0]
    if delta_params:
        for i, param in enumerate(delta_params):
            color = colors[i % len(colors)]
            # For multivariate parameters, merge across chains
            values = idata.posterior[param].values
            if values.ndim == 3:  # (chain, draw, possibly_channel)
                if values.shape[-1] == 1:
                    values = values.squeeze(-1)  # Remove singleton dimension
                else:
                    values = values.reshape(
                        values.shape[0] * values.shape[1], -1
                    )  # Flatten chain/draw dims
                    if values.shape[-1] > 1:  # Multiple values per timestep
                        values = values.mean(
                            axis=-1
                        )  # Average across channels if needed
                    else:
                        values = values.flatten()
            elif values.ndim == 2:  # (chain, draw)
                values = values.flatten()

            ax.plot(values, color=color, alpha=0.7, linewidth=1, label=param)
        ax.set_ylabel("Delta Parameters")
        ax.set_title("Delta Parameters Trace")
        ax.legend(loc="upper right", fontsize="small")
        ax.grid(True, alpha=0.3)
    else:
        ax.text(
            0.5,
            0.5,
            "No delta parameters found",
            ha="center",
            va="center",
            transform=ax.transAxes,
        )
        ax.set_title("Delta Parameters")
        ax.axis("off")

    # Plot phi parameters
    ax = axes[1]
    if phi_params:
        for i, param in enumerate(phi_params):
            color = colors[i % len(colors)]
            # For multivariate parameters, merge across chains
            values = idata.posterior[param].values
            if values.ndim == 3:  # (chain, draw, possibly_channel)
                if values.shape[-1] == 1:
                    values = values.squeeze(-1)  # Remove singleton dimension
                else:
                    values = values.reshape(
                        values.shape[0] * values.shape[1], -1
                    )  # Flatten chain/draw dims
                    if values.shape[-1] > 1:  # Multiple values per timestep
                        values = values.mean(
                            axis=-1
                        )  # Average across channels if needed
                    else:
                        values = values.flatten()
            elif values.ndim == 2:  # (chain, draw)
                values = values.flatten()

            ax.plot(values, color=color, alpha=0.7, linewidth=1, label=param)
        ax.set_ylabel("Phi Parameters")
        ax.set_title("Phi Parameters Trace")
        ax.legend(loc="upper right", fontsize="small")
        ax.grid(True, alpha=0.3)
    else:
        ax.text(
            0.5,
            0.5,
            "No phi parameters found",
            ha="center",
            va="center",
            transform=ax.transAxes,
        )
        ax.set_title("Phi Parameters")
        ax.axis("off")

    # Plot weights parameters (these are higher dimensional)
    ax = axes[2]
    if weights_params:
        # For weights, we'll show the mean across weight dimensions if they have shape (chain, draw, weight_dim)
        max_traces = min(
            10, len(weights_params)
        )  # Limit number of weight parameters to show
        for i, param in enumerate(weights_params[:max_traces]):
            color = colors[i % len(colors)]
            values = idata.posterior[param].values

            # Handle different dimensionalities
            if values.ndim == 4:  # (chain, draw, dim1, dim2)
                values = values.mean(axis=-1).mean(axis=-1).flatten()
            elif values.ndim == 3:  # (chain, draw, weight_dim)
                values = values.mean(
                    axis=-1
                ).flatten()  # Average across weight dimension
            elif values.ndim == 2:  # (chain, draw)
                values = values.flatten()

            ax.plot(values, color=color, alpha=0.7, linewidth=1, label=param)

        if len(weights_params) > max_traces:
            ax.text(
                0.02,
                0.02,
                f"Showing {max_traces} of {len(weights_params)} weight parameters",
                transform=ax.transAxes,
                fontsize="small",
                bbox=dict(boxstyle="round", facecolor="lightcoral", alpha=0.7),
            )

        ax.set_xlabel("Iteration")
        ax.set_ylabel("Weights Parameters (mean)")
        ax.set_title("Weights Parameters Trace (averaged)")
        ax.legend(loc="upper right", fontsize="small")
        ax.grid(True, alpha=0.3)
    else:
        ax.text(
            0.5,
            0.5,
            "No weights parameters found",
            ha="center",
            va="center",
            transform=ax.transAxes,
        )
        ax.set_title("Weights Parameters")
        ax.axis("off")

    plt.tight_layout()


def _group_parameters_simple(idata):
    """Simple parameter grouping for counting."""
    param_groups = {"phi": [], "delta": [], "weights": [], "other": []}

    for param in idata.posterior.data_vars:
        if param.startswith("phi"):
            param_groups["phi"].append(param)
        elif param.startswith("delta"):
            param_groups["delta"].append(param)
        elif param.startswith("weights"):
            param_groups["weights"].append(param)
        else:
            param_groups["other"].append(param)

    return {k: v for k, v in param_groups.items() if v}


def generate_diagnostics_summary(idata, outdir):
    """Generate comprehensive text summary."""
    summary = []
    summary.append("=== MCMC Diagnostics Summary ===\n")

    # Basic info
    attrs = getattr(idata, "attrs", {}) or {}
    if not hasattr(attrs, "get"):
        attrs = dict(attrs)

    n_samples = idata.posterior.sizes.get("draw", 0)
    n_chains = idata.posterior.sizes.get("chain", 1)
    n_params = len(list(idata.posterior.data_vars))
    sampler_type = attrs.get("sampler_type", "Unknown")

    summary.append(f"Sampler: {sampler_type}")
    summary.append(
        f"Samples: {n_samples} per chain × {n_chains} chains = {n_samples * n_chains} total"
    )
    summary.append(f"Parameters: {n_params}")

    # Parameter breakdown
    param_groups = _group_parameters_simple(idata)
    if param_groups:
        param_summary = ", ".join(
            [f"{k}: {len(v)}" for k, v in param_groups.items()]
        )
        summary.append(f"Parameter groups: {param_summary}")

    # ESS
    try:
        ess = az.ess(idata).to_array().values.flatten()
        ess_values = ess[~np.isnan(ess)]

        if len(ess_values) > 0:
            summary.append(
                f"\nESS: min={ess_values.min():.0f}, mean={ess_values.mean():.0f}, max={ess_values.max():.0f}"
            )
            summary.append(f"ESS ≥ 400: {(ess_values >= 400).mean()*100:.1f}%")
    except Exception as e:
        summary.append(f"\nESS: unavailable")

    # R-hat
    try:
        rhat = az.rhat(idata).to_array().values.flatten()
        rhat_values = rhat[~np.isnan(rhat)]

        if len(rhat_values) > 0:
            summary.append(
                f"R-hat: max={rhat_values.max():.3f}, mean={rhat_values.mean():.3f}"
            )
            summary.append(
                f"R-hat > 1.01: {(rhat_values > 1.01).mean()*100:.1f}%"
            )
    except Exception:
        summary.append(f"R-hat: unavailable")

    # Acceptance
    accept_key = None
    if "accept_prob" in idata.sample_stats:
        accept_key = "accept_prob"
    elif "acceptance_rate" in idata.sample_stats:
        accept_key = "acceptance_rate"

    if accept_key is not None:
        accept_rate = idata.sample_stats[accept_key].values.mean()
        target_rate = attrs.get(
            "target_accept_rate", attrs.get("target_accept_prob", 0.44)
        )
        summary.append(
            f"Acceptance rate: {accept_rate:.3f} (target: {target_rate:.3f})"
        )

    # PSD accuracy diagnostics (requires true_psd in attrs)
    has_true_psd = "true_psd" in attrs

    if has_true_psd:
        coverage_level = attrs.get("coverage_level")
        coverage_label = (
            f"{int(round(coverage_level * 100))}% interval coverage"
            if coverage_level is not None
            else "Interval coverage"
        )

        def _format_riae_line(value, errorbars, prefix="  "):
            line = f"{prefix}RIAE: {value:.3f}"
            if errorbars:
                q05, q25, median, q75, q95 = errorbars
                line += f" (median {median:.3f}, 5-95% [{q05:.3f}, {q95:.3f}])"
            summary.append(line)

        def _format_coverage_line(value, prefix="  "):
            if value is None:
                return
            summary.append(f"{prefix}{coverage_label}: {value * 100:.1f}%")

        summary.append("\nPSD accuracy diagnostics:")

        if "riae" in attrs:
            _format_riae_line(attrs["riae"], attrs.get("riae_errorbars"))
        if "coverage" in attrs:
            _format_coverage_line(attrs["coverage"])

        channel_indices = sorted(
            int(key.replace("riae_ch", ""))
            for key in attrs.keys()
            if key.startswith("riae_ch")
        )

        for idx in channel_indices:
            metrics = []
            riae_key = f"riae_ch{idx}"
            cov_key = f"coverage_ch{idx}"
            error_key = f"riae_errorbars_ch{idx}"

            if riae_key in attrs:
                riae_line = f"RIAE {attrs[riae_key]:.3f}"
                errorbars = attrs.get(error_key)
                if errorbars:
                    q05, _, median, _, q95 = errorbars
                    riae_line += (
                        f" (median {median:.3f}, 5-95% [{q05:.3f}, {q95:.3f}])"
                    )
                metrics.append(riae_line)

            if cov_key in attrs:
                metrics.append(f"{coverage_label} {attrs[cov_key] * 100:.1f}%")

            if metrics:
                summary.append(f"  Channel {idx}: " + "; ".join(metrics))

    # Overall assessment
    try:
        if len(ess_values) > 0 and len(rhat_values) > 0:
            ess_good = (ess_values >= 400).mean() * 100
            rhat_good = (rhat_values <= 1.01).mean() * 100

            summary.append(f"\nOverall Convergence Assessment:")
            if ess_good >= 90 and rhat_good >= 90:
                summary.append("  Status: EXCELLENT ✓")
            elif ess_good >= 75 and rhat_good >= 75:
                summary.append("  Status: GOOD ✓")
            else:
                summary.append("  Status: NEEDS ATTENTION ⚠")
    except:
        pass

    summary_text = "\n".join(summary)

    if outdir:
        with open(f"{outdir}/diagnostics_summary.txt", "w") as f:
            f.write(summary_text)

    print("\n" + summary_text + "\n")
    return summary_text

nz-gravity / LogPSplinePSD / 18160054724

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