PERF: Fixed performance regression in Series init

Closes pandas-dev#30564
TomAugspurger · Dec 30, 2019 · dc9a20d · dc9a20d
1 parent 733eb77
commit dc9a20d
Show file tree

Hide file tree

Showing 2 changed files with 8 additions and 1 deletion.
diff --git a/pandas/core/dtypes/dtypes.py b/pandas/core/dtypes/dtypes.py
@@ -882,7 +882,11 @@ def construct_from_string(cls, string):
                 return cls(freq=string)
             except ValueError:
                 pass
-        raise TypeError(f"Cannot construct a 'PeriodDtype' from '{string}'")
+        if isinstance(string, str):
+            msg = f"Cannot construct a 'PeriodDtype' from '{string}'"
+        else:
+            msg = f"'construct_from_string' expects a string, got {type(string)}"
+        raise TypeError(msg)
 
     def __str__(self) -> str_type:
         return self.name

diff --git a/pandas/tests/dtypes/test_dtypes.py b/pandas/tests/dtypes/test_dtypes.py
@@ -408,6 +408,9 @@ def test_construction_from_string(self):
         with pytest.raises(TypeError):
             PeriodDtype.construct_from_string("datetime64[ns, US/Eastern]")
 
+        with pytest.raises(TypeError, match="list"):
+            PeriodDtype.construct_from_string([1, 2, 3])
+
     def test_is_dtype(self):
         assert PeriodDtype.is_dtype(self.dtype)
         assert PeriodDtype.is_dtype("period[D]")