Merge pull request numpy#27364 from Kh4L/stack_doc_input_update

DOC: Update np.*stack doc to reflect behavior

Author: mhvk

numpy/_core/shape_base.py

@@ -235,7 +235,9 @@ def vstack(tup, *, dtype=None, casting="same_kind"):
     ----------
     tup : sequence of ndarrays
         The arrays must have the same shape along all but the first axis.
-        1-D arrays must have the same length.
+        1-D arrays must have the same length. In the case of a single
+        array_like input, it will be treated as a sequence of arrays; i.e.,
+        each element along the zeroth axis is treated as a separate array.
 
     dtype : str or dtype
         If provided, the destination array will have this dtype. Cannot be
@@ -308,7 +310,9 @@ def hstack(tup, *, dtype=None, casting="same_kind"):
     ----------
     tup : sequence of ndarrays
         The arrays must have the same shape along all but the second axis,
-        except 1-D arrays which can be any length.
+        except 1-D arrays which can be any length. In the case of a single
+        array_like input, it will be treated as a sequence of arrays; i.e.,
+        each element along the zeroth axis is treated as a separate array.
 
     dtype : str or dtype
         If provided, the destination array will have this dtype. Cannot be
@@ -384,8 +388,10 @@ def stack(arrays, axis=0, out=None, *, dtype=None, casting="same_kind"):
 
     Parameters
     ----------
-    arrays : sequence of array_like
-        Each array must have the same shape.
+    arrays : sequence of ndarrays
+        Each array must have the same shape. In the case of a single ndarray
+        array_like input, it will be treated as a sequence of arrays; i.e.,
+        each element along the zeroth axis is treated as a separate array.
 
     axis : int, optional
         The axis in the result array along which the input arrays are stacked.