Make data attribute on output FacetGrid have original column names

seaborn/relational.py

@@ -883,7 +883,7 @@ def relplot(
     if "ax" in kwargs:
         msg = (
             "relplot is a figure-level function and does not accept "
-            "the ax= paramter. You may wish to try {}".format(kind + "plot")
+            "the `ax` parameter. You may wish to try {}".format(kind + "plot")
         )
         warnings.warn(msg, UserWarning)
         kwargs.pop("ax")
@@ -965,12 +965,12 @@ def relplot(
     # Rename the columns of the plot_data structure appropriately
     new_cols = plot_variables.copy()
     new_cols.update(grid_kws)
-    full_data = p.plot_data.dropna(axis=1, how="all").rename(columns=new_cols)
+    full_data = p.plot_data.rename(columns=new_cols)
 
     # Set up the FacetGrid object
     facet_kws = {} if facet_kws is None else facet_kws.copy()
     g = FacetGrid(
-        data=full_data,
+        data=full_data.dropna(axis=1, how="all"),
         **grid_kws,
         col_wrap=col_wrap, row_order=row_order, col_order=col_order,
         height=height, aspect=aspect, dropna=False,
@@ -997,6 +997,13 @@ def relplot(
                          title=p.legend_title,
                          adjust_subtitles=True)
 
+    # Rename the columns of the FacetGrid's `data` attribute
+    # to match the original column names
+    orig_cols = {
+        f"_{k}": f"_{k}_" if v is None else v for k, v in variables.items()
+    }
+    g.data = g.data.rename(columns=orig_cols)
+
     return g
 
 

seaborn/tests/test_relational.py

@@ -617,6 +617,16 @@ def test_relplot_legend(self, long_df):
         for line, color in zip(lines, palette):
             assert line.get_color() == color
 
+    def test_relplot_data_columns(self, long_df):
+
+        long_df = long_df.assign(x_var=long_df["x"], y_var=long_df["y"])
+        g = relplot(
+            data=long_df,
+            x="x_var", y="y_var",
+            hue=long_df["a"].to_numpy(), col="c"
+        )
+        assert g.data.columns.to_list() == ["x_var", "y_var", "_hue_", "c"]
+
     def test_facet_variable_collision(self, long_df):
 
         # https://github.com/mwaskom/seaborn/issues/2488