diff options
Diffstat (limited to 'numpy/core/fromnumeric.py')
| -rw-r--r-- | numpy/core/fromnumeric.py | 38 |
1 files changed, 37 insertions, 1 deletions
diff --git a/numpy/core/fromnumeric.py b/numpy/core/fromnumeric.py index 5f7716455..6e5f3dabf 100644 --- a/numpy/core/fromnumeric.py +++ b/numpy/core/fromnumeric.py @@ -796,7 +796,9 @@ def argpartition(a, kth, axis=-1, kind='introselect', order=None): -------- partition : Describes partition algorithms used. ndarray.partition : Inplace partition. - argsort : Full indirect sort + argsort : Full indirect sort. + take_along_axis : Apply ``index_array`` from argpartition + to an array as if by calling partition. Notes ----- @@ -816,6 +818,14 @@ def argpartition(a, kth, axis=-1, kind='introselect', order=None): >>> np.array(x)[np.argpartition(x, 3)] array([2, 1, 3, 4]) + Multi-dimensional array: + + >>> x = np.array([[3, 4, 2], [1, 3, 1]]) + >>> index_array = np.argpartition(x, kth=1, axis=-1) + >>> np.take_along_axis(x, index_array, axis=-1) # same as np.partition(x, kth=1) + array([[2, 3, 4], + [1, 1, 3]]) + """ return _wrapfunc(a, 'argpartition', kth, axis=axis, kind=kind, order=order) @@ -1025,6 +1035,8 @@ def argsort(a, axis=-1, kind=None, order=None): lexsort : Indirect stable sort with multiple keys. ndarray.sort : Inplace sort. argpartition : Indirect partial sort. + take_along_axis : Apply ``index_array`` from argsort + to an array as if by calling sort. Notes ----- @@ -1120,6 +1132,8 @@ def argmax(a, axis=None, out=None): ndarray.argmax, argmin amax : The maximum value along a given axis. unravel_index : Convert a flat index into an index tuple. + take_along_axis : Apply ``np.expand_dims(index_array, axis)`` + from argmax to an array as if by calling max. Notes ----- @@ -1154,6 +1168,16 @@ def argmax(a, axis=None, out=None): >>> np.argmax(b) # Only the first occurrence is returned. 1 + >>> x = np.array([[4,2,3], [1,0,3]]) + >>> index_array = np.argmax(x, axis=-1) + >>> # Same as np.max(x, axis=-1, keepdims=True) + >>> np.take_along_axis(x, np.expand_dims(index_array, axis=-1), axis=-1) + array([[4], + [3]]) + >>> # Same as np.max(x, axis=-1) + >>> np.take_along_axis(x, np.expand_dims(index_array, axis=-1), axis=-1).squeeze(axis=-1) + array([4, 3]) + """ return _wrapfunc(a, 'argmax', axis=axis, out=out) @@ -1189,6 +1213,8 @@ def argmin(a, axis=None, out=None): ndarray.argmin, argmax amin : The minimum value along a given axis. unravel_index : Convert a flat index into an index tuple. + take_along_axis : Apply ``np.expand_dims(index_array, axis)`` + from argmin to an array as if by calling min. Notes ----- @@ -1223,6 +1249,16 @@ def argmin(a, axis=None, out=None): >>> np.argmin(b) # Only the first occurrence is returned. 0 + >>> x = np.array([[4,2,3], [1,0,3]]) + >>> index_array = np.argmin(x, axis=-1) + >>> # Same as np.min(x, axis=-1, keepdims=True) + >>> np.take_along_axis(x, np.expand_dims(index_array, axis=-1), axis=-1) + array([[2], + [0]]) + >>> # Same as np.max(x, axis=-1) + >>> np.take_along_axis(x, np.expand_dims(index_array, axis=-1), axis=-1).squeeze(axis=-1) + array([2, 0]) + """ return _wrapfunc(a, 'argmin', axis=axis, out=out) |