#24605 add check to validate loc tuples

jpjepko · jpjepko · commit 03813be9b596 · 2022-12-11T04:27:49.000-05:00
diff --git a/lib/matplotlib/legend.py b/lib/matplotlib/legend.py
@@ -472,6 +472,14 @@ def val_or_rc(val, rc_name):
                 loc = 'upper right'
         if isinstance(loc, str):
             loc = _api.check_getitem(self.codes, loc=loc)
+        elif isinstance(loc, tuple):
+            if len(loc) != 2:
+                raise ValueError(
+                    "loc must be string or pair of floats")
+            for loc_elt in loc:
+                # int can be converted to float, so ints are fine
+                if not isinstance(loc_elt, (float, int)):
+                    raise ValueError(f"{loc_elt} is not a valid value for loc")
         if not self.isaxes and loc == 0:
             raise ValueError(
                 "Automatic legend placement (loc='best') not implemented for "
diff --git a/lib/matplotlib/tests/test_legend.py b/lib/matplotlib/tests/test_legend.py
@@ -1090,3 +1090,22 @@ def test_ncol_ncols(fig_test, fig_ref):
     ncols = 3
     fig_test.legend(strings, ncol=ncols)
     fig_ref.legend(strings, ncols=ncols)
+
+
+def test_loc_invalid_tuple_exception():
+    # check that exception is raised if the loc arg
+    # of legend is not a 2-tuple of numbers
+    fig, ax = plt.subplots()
+    with pytest.raises(ValueError,
+                       match="loc must be string or pair of floats"):
+        ax.legend(loc=(1.1, ))
+        ax.legend(loc=(0.481, 0.4227, 0.4523))
+    with pytest.raises(ValueError,
+                       match="go blue is not a valid value for loc"):
+        ax.legend(loc=(0.481, "go blue"))
+
+
+def test_loc_valid_tuple():
+    fig, ax = plt.subplots()
+    ax.legend(loc=(0.481, 0.442))
+    ax.legend(loc=(1, 2))
