Backport PR #48426 on branch 1.5.x (BUG: Column.size should be a method) (#48465)

Backport PR #48426: BUG: Column.size should be a method

Co-authored-by: Matthew Roeschke <[email protected]>

Author: meeseeksmachine

pandas/core/interchange/column.py

@@ -81,7 +81,6 @@ def __init__(self, column: pd.Series, allow_copy: bool = True) -> None:
         self._col = column
         self._allow_copy = allow_copy
 
-    @property
     def size(self) -> int:
         """
         Size of the column, in elements.

pandas/tests/interchange/test_impl.py

@@ -164,14 +164,14 @@ def test_string():
     df = pd.DataFrame({"A": test_str_data})
     col = df.__dataframe__().get_column_by_name("A")
 
-    assert col.size == 6
+    assert col.size() == 6
     assert col.null_count == 1
     assert col.dtype[0] == DtypeKind.STRING
     assert col.describe_null == (ColumnNullType.USE_BYTEMASK, 0)
 
     df_sliced = df[1:]
     col = df_sliced.__dataframe__().get_column_by_name("A")
-    assert col.size == 5
+    assert col.size() == 5
     assert col.null_count == 1
     assert col.dtype[0] == DtypeKind.STRING
     assert col.describe_null == (ColumnNullType.USE_BYTEMASK, 0)
@@ -188,7 +188,7 @@ def test_datetime():
     df = pd.DataFrame({"A": [pd.Timestamp("2022-01-01"), pd.NaT]})
     col = df.__dataframe__().get_column_by_name("A")
 
-    assert col.size == 2
+    assert col.size() == 2
     assert col.null_count == 1
     assert col.dtype[0] == DtypeKind.DATETIME
     assert col.describe_null == (ColumnNullType.USE_SENTINEL, iNaT)

pandas/tests/interchange/test_spec_conformance.py

@@ -27,7 +27,7 @@ def test_only_one_dtype(test_data, df_from_dict):
         null_count = dfX.get_column_by_name(column).null_count
         assert null_count == 0
         assert isinstance(null_count, int)
-        assert dfX.get_column_by_name(column).size == column_size
+        assert dfX.get_column_by_name(column).size() == column_size
         assert dfX.get_column_by_name(column).offset == 0
 
 
@@ -52,7 +52,7 @@ def test_mixed_dtypes(df_from_dict):
         colX = dfX.get_column_by_name(column)
         assert colX.null_count == 0
         assert isinstance(colX.null_count, int)
-        assert colX.size == 3
+        assert colX.size() == 3
         assert colX.offset == 0
 
         assert colX.dtype[0] == kind
@@ -118,14 +118,14 @@ def test_column_get_chunks(size, n_chunks, df_from_dict):
     dfX = df.__dataframe__()
     chunks = list(dfX.get_column(0).get_chunks(n_chunks))
     assert len(chunks) == n_chunks
-    assert sum(chunk.size for chunk in chunks) == size
+    assert sum(chunk.size() for chunk in chunks) == size
 
 
 def test_get_columns(df_from_dict):
     df = df_from_dict({"a": [0, 1], "b": [2.5, 3.5]})
     dfX = df.__dataframe__()
     for colX in dfX.get_columns():
-        assert colX.size == 2
+        assert colX.size() == 2
         assert colX.num_chunks() == 1
     # for meanings of dtype[0] see the spec; we cannot import the spec here as this
     # file is expected to be vendored *anywhere*