fix: allow overwriting labels for plot/overlay

Author: andrzejnovak

src/hist/basehist.py

@@ -417,6 +417,15 @@ 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 and hasattr(kwargs['label'], 'len'):
+            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(