Don't evaluate entities if no entities present in test data

changelog/8812.bugfix.md

@@ -0,0 +1,3 @@
+Don't evaluate entities if no entities present in test data.
+
+Also, catch exception in `plot_paired_histogram` when data is empty.

rasa/nlu/test.py

@@ -1264,7 +1264,9 @@ def get_eval_data(
         interpreter
     )
 
-    should_eval_entities = is_entity_extractor_present(interpreter)
+    should_eval_entities = (
+        is_entity_extractor_present(interpreter) and len(test_data.entities) > 0
+    )
 
     for example in tqdm(test_data.nlu_examples):
         result = interpreter.parse(example.get(TEXT), only_output_properties=False)

rasa/utils/plotting.py

@@ -163,7 +163,13 @@ def _extract_paired_histogram_specification(
 
     Returns:
         The bins, values, ranges of either x-axis, and the range of the y-axis
+
+    Raises:
+        ValueError: If histogram_data does not contain values.
     """
+    if not histogram_data or not np.concatenate(histogram_data).size:
+        rasa.shared.utils.io.raise_warning("No data to plot paired histogram.")
+        raise ValueError("No data to plot paired histogram.")
     min_data_value = np.min(np.concatenate(histogram_data))
     max_data_value = np.max(np.concatenate(histogram_data))
     bin_width = (max_data_value - min_data_value) / num_bins
@@ -244,13 +250,19 @@ def plot_paired_histogram(
         )
         return
 
-    bins, tallies, x_ranges, y_range = _extract_paired_histogram_specification(
-        histogram_data,
-        num_bins,
-        density=density,
-        x_pad_fraction=x_pad_fraction,
-        y_pad_fraction=y_pad_fraction,
-    )
+    try:
+        bins, tallies, x_ranges, y_range = _extract_paired_histogram_specification(
+            histogram_data,
+            num_bins,
+            density=density,
+            x_pad_fraction=x_pad_fraction,
+            y_pad_fraction=y_pad_fraction,
+        )
+    except ValueError as e:
+        rasa.shared.utils.io.raise_warning(
+            f"Unable to plot paired histogram '{title}': {e}"
+        )
+        return
     yticks = [float(f"{x:.2f}") for x in bins]
 
     import matplotlib.pyplot as plt

tests/utils/test_plotting.py

@@ -29,6 +29,36 @@ def test_paired_histogram_specification_bins(
         assert np.all(bins == expected_bins)
 
 
+@pytest.mark.parametrize(
+    "bad_data", [([[]]), ([[], []]),],
+)
+def test_paired_histogram_specification_bins_raises(bad_data: List):
+    """`_extract_paired_histogram_specification` raises a ValueError on empty data"""
+    for density in [False, True]:
+        with pytest.raises(ValueError):
+            rasa.utils.plotting._extract_paired_histogram_specification(
+                bad_data,
+                num_bins=2,
+                density=density,
+                x_pad_fraction=0,
+                y_pad_fraction=0,
+            )
+
+
+@pytest.mark.parametrize(
+    "bad_data", [([[]]), ([[], []]),],
+)
+def test_plot_paired_histogram_warns_on_bad_data(bad_data: List):
+    """Empty data shouldn't raise an error."""
+    for density in [False, True]:
+        with pytest.warns(
+            UserWarning, match=r"Unable to plot paired histogram 'TITLE': .*"
+        ):
+            rasa.utils.plotting.plot_paired_histogram(
+                bad_data, title="TITLE", density=density
+            )
+
+
 @pytest.mark.parametrize(
     "data, num_bins, density, expected_histograms",
     [