DOC: Clear up confusion between np.where(cond) and np.where(cond, x, y)

Eliminates all mentions of `np.where(cond)`, instead pointing the reader to np.nonzero.

Also changes some example numbers to avoid collisions, making them easier to follow.

Some minor doc improvements for np.ma.where too.

1 files changed, 8 insertions, 0 deletions

diff --git a/numpy/lib/arraysetops.py b/numpy/lib/arraysetops.py
index 4d3f35183..5880ea154 100644
--- a/numpy/lib/arraysetops.py
+++ b/numpy/lib/arraysetops.py
@@ -607,6 +607,14 @@ def isin(element, test_elements, assume_unique=False, invert=False):
            [ True,  False]])
     >>> element[mask]
     array([2, 4])
+
+    The indices of the matched values can be obtained with `nonzero`:
+
+    >>> np.nonzero(mask)
+    (array([0, 1]), array([1, 0]))
+
+    The test can also be inverted:
+
     >>> mask = np.isin(element, test_elements, invert=True)
     >>> mask
     array([[ True, False],