Merge pull request #160 from pandas-dev/master

DOC: Clarify DataFrame column argument in API documentation (pandas-dev#40658)

Author: sthagen

pandas/core/frame.py

@@ -472,8 +472,9 @@ class DataFrame(NDFrame, OpsMixin):
         Index to use for resulting frame. Will default to RangeIndex if
         no indexing information part of input data and no index provided.
     columns : Index or array-like
-        Column labels to use for resulting frame. Will default to
-        RangeIndex (0, 1, 2, ..., n) if no column labels are provided.
+        Column labels to use for resulting frame when data does not have them,
+        defaulting to RangeIndex(0, 1, 2, ..., n). If data contains column labels,
+        will perform column selection instead.
     dtype : dtype, default None
         Data type to force. Only a single dtype is allowed. If None, infer.
     copy : bool or None, default None
@@ -527,6 +528,18 @@ class DataFrame(NDFrame, OpsMixin):
     1  4  5  6
     2  7  8  9
 
+    Constructing DataFrame from a numpy ndarray that has labeled columns:
+
+    >>> data = np.array([(1, 2, 3), (4, 5, 6), (7, 8, 9)],
+    ...                 dtype=[("a", "i4"), ("b", "i4"), ("c", "i4")])
+    >>> df3 = pd.DataFrame(data, columns=['c', 'a'])
+    ...
+    >>> df3
+       c  a
+    0  3  1
+    1  6  4
+    2  9  7
+
     Constructing DataFrame from dataclass:
 
     >>> from dataclasses import make_dataclass