ENH/BUG: DataFrame(object_array_of_periods_or_intervals) (#41812)

Author: jbrockmendel

doc/source/whatsnew/v1.3.0.rst

@@ -892,6 +892,7 @@ Conversion
 - Bug in :meth:`qcut` raising error when taking ``Float64DType`` as input (:issue:`40730`)
 - Bug in :class:`DataFrame` and :class:`Series` construction with ``datetime64[ns]`` data and ``dtype=object`` resulting in ``datetime`` objects instead of :class:`Timestamp` objects (:issue:`41599`)
 - Bug in :class:`DataFrame` and :class:`Series` construction with ``timedelta64[ns]`` data and ``dtype=object`` resulting in ``np.timedelta64`` objects instead of :class:`Timedelta` objects (:issue:`41599`)
+- Bug in :class:`DataFrame` construction when given a two-dimensional object-dtype ``np.ndarray`` of :class:`Period` or :class:`Interval` objects failing to cast to :class:`PeriodDtype` or :class:`IntervalDtype`, respectively (:issue:`41812`)
 
 Strings
 ^^^^^^^

pandas/_libs/lib.pyi

@@ -73,6 +73,7 @@ def maybe_convert_objects(
     convert_datetime: Literal[False] = ...,
     convert_timedelta: bool = ...,
     convert_period: Literal[False] = ...,
+    convert_interval: Literal[False] = ...,
     convert_to_nullable_integer: Literal[False] = ...,
     dtype_if_all_nat: DtypeObj | None = ...,
 ) -> np.ndarray: ...
@@ -86,6 +87,7 @@ def maybe_convert_objects(
     convert_datetime: bool = ...,
     convert_timedelta: bool = ...,
     convert_period: bool = ...,
+    convert_interval: bool = ...,
     convert_to_nullable_integer: Literal[True] = ...,
     dtype_if_all_nat: DtypeObj | None = ...,
 ) -> ArrayLike: ...
@@ -99,6 +101,7 @@ def maybe_convert_objects(
     convert_datetime: Literal[True] = ...,
     convert_timedelta: bool = ...,
     convert_period: bool = ...,
+    convert_interval: bool = ...,
     convert_to_nullable_integer: bool = ...,
     dtype_if_all_nat: DtypeObj | None = ...,
 ) -> ArrayLike: ...
@@ -112,6 +115,7 @@ def maybe_convert_objects(
     convert_datetime: bool = ...,
     convert_timedelta: bool = ...,
     convert_period: Literal[True] = ...,
+    convert_interval: bool = ...,
     convert_to_nullable_integer: bool = ...,
     dtype_if_all_nat: DtypeObj | None = ...,
 ) -> ArrayLike: ...
@@ -125,6 +129,7 @@ def maybe_convert_objects(
     convert_datetime: bool = ...,
     convert_timedelta: bool = ...,
     convert_period: bool = ...,
+    convert_interval: bool = ...,
     convert_to_nullable_integer: bool = ...,
     dtype_if_all_nat: DtypeObj | None = ...,
 ) -> ArrayLike: ...

pandas/_libs/lib.pyx

@@ -1573,6 +1573,7 @@ def infer_datetimelike_array(arr: ndarray[object]) -> tuple[str, bool]:
         bint seen_timedelta = False, seen_date = False, seen_datetime = False
         bint seen_tz_aware = False, seen_tz_naive = False
         bint seen_nat = False, seen_str = False
+        bint seen_period = False, seen_interval = False
         list objs = []
         object v
 
@@ -1610,9 +1611,25 @@ def infer_datetimelike_array(arr: ndarray[object]) -> tuple[str, bool]:
         elif is_timedelta(v):
             # timedelta, or timedelta64
             seen_timedelta = True
+        elif is_period_object(v):
+            seen_period = True
+            break
+        elif is_interval(v):
+            seen_interval = True
+            break
         else:
             return "mixed", seen_str
 
+    if seen_period:
+        if is_period_array(arr):
+            return "period", seen_str
+        return "mixed", seen_str
+
+    if seen_interval:
+        if is_interval_array(arr):
+            return "interval", seen_str
+        return "mixed", seen_str
+
     if seen_date and not (seen_datetime or seen_timedelta):
         return "date", seen_str
     elif seen_datetime and not seen_timedelta:

pandas/core/construction.py

@@ -48,7 +48,6 @@
     is_integer_dtype,
     is_list_like,
     is_object_dtype,
-    is_string_dtype,
     is_timedelta64_ns_dtype,
 )
 from pandas.core.dtypes.dtypes import DatetimeTZDtype
@@ -565,18 +564,11 @@ def sanitize_array(
 
     subarr = _sanitize_ndim(subarr, data, dtype, index, allow_2d=allow_2d)
 
-    if not (
-        isinstance(subarr.dtype, ExtensionDtype) or isinstance(dtype, ExtensionDtype)
-    ):
+    if isinstance(subarr, np.ndarray):
+        # at this point we should have dtype be None or subarr.dtype == dtype
+        dtype = cast(np.dtype, dtype)
         subarr = _sanitize_str_dtypes(subarr, data, dtype, copy)
 
-        is_object_or_str_dtype = is_object_dtype(dtype) or is_string_dtype(dtype)
-        if is_object_dtype(subarr.dtype) and not is_object_or_str_dtype:
-            inferred = lib.infer_dtype(subarr, skipna=False)
-            if inferred in {"interval", "period"}:
-                subarr = array(subarr)
-                subarr = extract_array(subarr, extract_numpy=True)
-
     return subarr
 
 

pandas/core/dtypes/cast.py

@@ -1464,7 +1464,7 @@ def convert_dtypes(
 
 def maybe_infer_to_datetimelike(
     value: np.ndarray,
-) -> np.ndarray | DatetimeArray | TimedeltaArray:
+) -> np.ndarray | DatetimeArray | TimedeltaArray | PeriodArray | IntervalArray:
     """
     we might have a array (or single object) that is datetime like,
     and no dtype is passed don't change the value unless we find a
@@ -1479,7 +1479,7 @@ def maybe_infer_to_datetimelike(
 
     Returns
     -------
-    np.ndarray, DatetimeArray, or TimedeltaArray
+    np.ndarray, DatetimeArray, TimedeltaArray, PeriodArray, or IntervalArray
 
     """
     if not isinstance(value, np.ndarray) or value.dtype != object:
@@ -1528,6 +1528,13 @@ def try_timedelta(v: np.ndarray) -> np.ndarray:
             return td_values.reshape(shape)
 
     inferred_type, seen_str = lib.infer_datetimelike_array(ensure_object(v))
+    if inferred_type in ["period", "interval"]:
+        # Incompatible return value type (got "Union[ExtensionArray, ndarray]",
+        # expected "Union[ndarray, DatetimeArray, TimedeltaArray, PeriodArray,
+        # IntervalArray]")
+        return lib.maybe_convert_objects(  # type: ignore[return-value]
+            v, convert_period=True, convert_interval=True
+        )
 
     if inferred_type == "datetime":
         # error: Incompatible types in assignment (expression has type "ExtensionArray",
@@ -1564,7 +1571,6 @@ def try_timedelta(v: np.ndarray) -> np.ndarray:
             FutureWarning,
             stacklevel=find_stack_level(),
         )
-        # return v.reshape(shape)
     return value
 
 

pandas/tests/extension/base/reshaping.py

@@ -3,6 +3,11 @@
 import numpy as np
 import pytest
 
+from pandas.core.dtypes.common import (
+    is_interval_dtype,
+    is_period_dtype,
+)
+
 import pandas as pd
 from pandas.api.extensions import ExtensionArray
 from pandas.core.internals import ExtensionBlock
@@ -321,6 +326,14 @@ def test_unstack(self, data, index, obj):
             expected = ser.astype(object).unstack(
                 level=level, fill_value=data.dtype.na_value
             )
+            if obj == "series":
+                # TODO: special cases belong in dtype-specific tests
+                if is_period_dtype(data.dtype):
+                    assert expected.dtypes.apply(is_period_dtype).all()
+                    expected = expected.astype(object)
+                if is_interval_dtype(data.dtype):
+                    assert expected.dtypes.apply(is_interval_dtype).all()
+                    expected = expected.astype(object)
             result = result.astype(object)
 
             self.assert_frame_equal(result, expected)

pandas/tests/frame/test_constructors.py

@@ -2494,6 +2494,28 @@ def test_nested_list_columns(self):
         )
         tm.assert_frame_equal(result, expected)
 
+    def test_from_2d_object_array_of_periods_or_intervals(self):
+        # Period analogue to GH#26825
+        pi = pd.period_range("2016-04-05", periods=3)
+        data = pi._data.astype(object).reshape(1, -1)
+        df = DataFrame(data)
+        assert df.shape == (1, 3)
+        assert (df.dtypes == pi.dtype).all()
+        assert (df == pi).all().all()
+
+        ii = pd.IntervalIndex.from_breaks([3, 4, 5, 6])
+        data2 = ii._data.astype(object).reshape(1, -1)
+        df2 = DataFrame(data2)
+        assert df2.shape == (1, 3)
+        assert (df2.dtypes == ii.dtype).all()
+        assert (df2 == ii).all().all()
+
+        # mixed
+        data3 = np.r_[data, data2, data, data2].T
+        df3 = DataFrame(data3)
+        expected = DataFrame({0: pi, 1: ii, 2: pi, 3: ii})
+        tm.assert_frame_equal(df3, expected)
+
 
 class TestDataFrameConstructorWithDtypeCoercion:
     def test_floating_values_integer_dtype(self):

pandas/tests/tools/test_to_timedelta.py

@@ -208,7 +208,9 @@ def test_to_timedelta_on_missing_values(self):
         tm.assert_series_equal(actual, expected)
 
         with tm.assert_produces_warning(FutureWarning, match="Inferring timedelta64"):
-            actual = to_timedelta(Series(["00:00:01", pd.NaT]))
+            ser = Series(["00:00:01", pd.NaT])
+        assert ser.dtype == "m8[ns]"
+        actual = to_timedelta(ser)
         tm.assert_series_equal(actual, expected)
 
         actual = to_timedelta(np.nan)