Custom test quantity support for calibration_ecdf

bayesflow/diagnostics/plots/calibration_ecdf.py

@@ -1,6 +1,7 @@
-from collections.abc import Mapping, Sequence
+from collections.abc import Callable, Mapping, Sequence
 
 import numpy as np
+import keras
 import matplotlib.pyplot as plt
 
 from ...utils.plot_utils import prepare_plot_data, add_titles_and_labels, prettify_subplots
@@ -13,6 +14,7 @@ def calibration_ecdf(
     targets: Mapping[str, np.ndarray] | np.ndarray,
     variable_keys: Sequence[str] = None,
     variable_names: Sequence[str] = None,
+    test_quantities: dict[str, Callable] = None,
     difference: bool = False,
     stacked: bool = False,
     rank_type: str | np.ndarray = "fractional",
@@ -78,6 +80,18 @@ def calibration_ecdf(
     variable_names    : list or None, optional, default: None
         The parameter names for nice plot titles.
         Inferred if None. Only relevant if `stacked=False`.
+    test_quantities   : dict or None, optional, default: None
+        A dict that maps plot titles to functions that compute
+        test quantities based on estimate/target draws.
+
+        The dict keys are automatically added to ``variable_keys``
+        and ``variable_names``.
+        Test quantity functions are expected to accept a dict of draws with
+        shape ``(batch_size, ...)`` as the first (typically only)
+        positional argument and return an NumPy array of shape
+        ``(batch_size,)``.
+        The functions do not have to deal with an additional
+        sample dimension, as appropriate reshaping is done internally.
     figsize           : tuple or None, optional, default: None
         The figure size passed to the matplotlib constructor.
         Inferred if None.
@@ -120,6 +134,32 @@ def calibration_ecdf(
         If an unknown `rank_type` is passed.
     """
 
+    # Optionally, compute and prepend test quantities from draws
+    if test_quantities is not None:
+        # Prepare empty mapping to hold test quantity values
+        test_quantities_estimates = {}
+        test_quantities_targets = {}
+
+        for key, test_quantity_func in test_quantities.items():
+            # Apply test_quantity_func to draws
+            tq_targets = test_quantity_func(data=targets)
+            test_quantities_targets[key] = np.expand_dims(tq_targets, axis=1)
+
+            # We assume test_quantity_func can only handle a 1D batch_size, so estimates
+            # which have shape (num_conditions, num_samples, ...) must be flattend first.
+            num_conditions, num_samples = next(iter(estimates.values())).shape[:2]
+            flattened_estimates = keras.tree.map_structure(lambda t: np.reshape(t, (-1, *t.shape[2:])), estimates)
+            flat_tq_estimates = test_quantity_func(data=flattened_estimates)
+            test_quantities_estimates[key] = np.reshape(flat_tq_estimates, (num_conditions, num_samples, 1))
+
+        # Add custom test quantities to variable keys and names for plotting
+        variable_keys = list(test_quantities.keys()) + variable_keys
+        variable_names = list(test_quantities.keys()) + variable_names
+
+        # Prepend test quantities to draws
+        estimates = test_quantities_estimates | estimates
+        targets = test_quantities_targets | targets
+
     plot_data = prepare_plot_data(
         estimates=estimates,
         targets=targets,