feat: plot1d for hist(cat,reg)

src/hist/basehist.py

@@ -297,12 +297,16 @@ def show(self, **kwargs: Any) -> Any:
 
         return histoprint.print_hist(self, **kwargs)
 
-    def plot(self, *args: Any, **kwargs: Any) -> "Union[Hist1DArtists, Hist2DArtists]":
+    def plot(
+        self, *args: Any, overlay: "Optional[str]" = None, **kwargs: Any
+    ) -> "Union[Hist1DArtists, Hist2DArtists]":
         """
         Plot method for BaseHist object.
         """
-        if self.ndim == 1:
-            return self.plot1d(*args, **kwargs)
+        _has_categorical = np.sum([ax.traits.discrete for ax in self.axes]) == 1
+        _project = _has_categorical or overlay is not None
+        if self.ndim == 1 or (self.ndim == 2 and _project):
+            return self.plot1d(*args, overlay=overlay, **kwargs)
         elif self.ndim == 2:
             return self.plot2d(*args, **kwargs)
         else:
@@ -312,6 +316,7 @@ def plot1d(
         self,
         *,
         ax: "Optional[matplotlib.axes.Axes]" = None,
+        overlay: "Optional[Union[str, int]]" = None,
         **kwargs: Any,
     ) -> "Hist1DArtists":
         """
@@ -320,7 +325,15 @@ def plot1d(
 
         import hist.plot
 
-        return hist.plot.histplot(self, ax=ax, **_proc_kw_for_lw(kwargs))
+        if self.ndim == 1:
+            return hist.plot.histplot(self, ax=ax, **_proc_kw_for_lw(kwargs))
+        if overlay is None:
+            (overlay,) = (i for i, ax in enumerate(self.axes) if ax.traits.discrete)
+        assert overlay is not None
+        cat_ax = self.axes[overlay]
+        cats = cat_ax if cat_ax.traits.discrete else np.arange(len(cat_ax.centers))
+        d1hists = [self[{overlay: cat}] for cat in cats]
+        return hist.plot.histplot(d1hists, ax=ax, label=cats, **_proc_kw_for_lw(kwargs))
 
     def plot2d(
         self,

tests/test_plot.py

@@ -623,3 +623,42 @@ def pdf(x, a=1 / np.sqrt(2 * np.pi), x0=0, sigma=1, offset=0):
     assert h.plot_pull(pdf, fit_fmt=r"{name} = {value:.3g} $\pm$ {error:.3g}")
 
     return fig
+
+
+@pytest.mark.mpl_image_compare(baseline_dir="baseline", savefig_kwargs={"dpi": 50})
+def test_plot1d_auto_handling():
+    """
+    Test plot() by comparing against a reference image generated via
+    `pytest --mpl-generate-path=tests/baseline`
+    """
+
+    np.random.seed(42)
+
+    h = Hist(
+        axis.Regular(10, 0, 10, name="variable", label="variable"),
+        axis.StrCategory("", name="dataset", growth=True),
+    )
+
+    h_nameless = Hist(
+        axis.Regular(10, 0, 10),
+        axis.StrCategory("", growth=True),
+    )
+
+    h.fill(dataset="A", variable=np.random.normal(3, 2, 100))
+    h.fill(dataset="B", variable=np.random.normal(5, 2, 100))
+    h.fill(dataset="C", variable=np.random.normal(7, 2, 100))
+
+    h_nameless.fill(np.random.normal(3, 2, 1000), "A")
+    h_nameless.fill(np.random.normal(5, 2, 1000), "B")
+    h_nameless.fill(np.random.normal(7, 2, 1000), "C")
+
+    fig, (ax1, ax2) = plt.subplots(2, 2, figsize=(14, 10))
+
+    assert h.plot(ax=ax1[0])
+    assert h_nameless.plot(ax=ax2[0])
+
+    # Discrete axis plotting not yet implemented
+    # assert h.plot(ax=ax1[1], overlay='variable')
+    # assert h.plot(ax=ax2[1], overlay=1)
+
+    return fig