Inherit errorbar alpha from scatter points in regplot (#2853)

* x_estimator bars now inherit scatter_kws alpha

x_estimator error bars were previously always opaque, but now inherit alpha settings from scatterplot settings, since the error bars replace the scatterplot

* Inherit errorbar alpha from scatter points in regplot

Closes #2540 by adding a test.

Co-authored-by: Milo Trujillo <milo-trujillo@users.noreply.github.com>

doc/releases/v0.12.0.txt

@@ -53,6 +53,8 @@ Other updates
 
 - |Enhancement| When using :func:`pairplot` with `corner=True` and `diag_kind=None`, the top left y axis label is no longer hidden (:pr:2850`).
 
+- |Enhancement| Error bars in :func:`regplot` now inherit the alpha value of the points they correspond to (:pr:`2540`).
+
 - |Fix| Fixed a regression in 0.11.2 that caused some functions to stall indefinitely or raise when the input data had a duplicate index (:pr:`2776`).
 
 - |Fix| Fixed a bug in :func:`histplot` and :func:`kdeplot` where weights were not factored into the normalization (:pr:`2812`).

seaborn/regression.py

@@ -396,6 +396,8 @@ def scatterplot(self, ax, kws):
         else:
             # TODO abstraction
             ci_kws = {"color": kws["color"]}
+            if "alpha" in kws:
+                ci_kws["alpha"] = kws["alpha"]
             ci_kws["linewidth"] = mpl.rcParams["lines.linewidth"] * 1.75
             kws.setdefault("s", 50)
 

tests/test_regression.py

@@ -522,6 +522,14 @@ def test_regplot_scatter_kws_alpha(self):
                         scatter_kws={'color': color})
         assert ax.collections[0]._alpha == 0.8
 
+        f, ax = plt.subplots()
+        alpha = .3
+        ax = lm.regplot(x="x", y="y", data=self.df,
+                        x_bins=5, fit_reg=False,
+                        scatter_kws={"alpha": alpha})
+        for line in ax.lines:
+            assert line.get_alpha() == alpha
+
     def test_regplot_binned(self):
 
         ax = lm.regplot(x="x", y="y", data=self.df, x_bins=5)