fix: allow overwriting labels for plot/overlay (#414)

* fix: allow overwriting labels for plot/overlay

* style: pre-commit fixes

* fix: review

Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>

Author: 3 people

src/hist/basehist.py

@@ -417,6 +417,19 @@ def plot1d(
         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]
+        if "label" in kwargs:
+            if not isinstance(kwargs["label"], str) and len(kwargs["label"]) == len(
+                cats
+            ):
+                cats = kwargs["label"]
+                kwargs.pop("label")
+            elif isinstance(kwargs["label"], str):
+                cats = [kwargs["label"]] * len(cats)
+                kwargs.pop("label")
+            else:
+                raise ValueError(
+                    f"label ``{kwargs['label']}`` not understood for {len(cats)} categories"
+                )
         return plot.histplot(d1hists, ax=ax, label=cats, **_proc_kw_for_lw(kwargs))
 
     def plot2d(