diff options
Diffstat (limited to 'numpy/core/fromnumeric.py')
| -rw-r--r-- | numpy/core/fromnumeric.py | 37 |
1 files changed, 30 insertions, 7 deletions
diff --git a/numpy/core/fromnumeric.py b/numpy/core/fromnumeric.py index f336ae248..acfe92a63 100644 --- a/numpy/core/fromnumeric.py +++ b/numpy/core/fromnumeric.py @@ -828,8 +828,16 @@ def sort(a, axis=-1, kind='quicksort', order=None): axis : int or None, optional Axis along which to sort. If None, the array is flattened before sorting. The default is -1, which sorts along the last axis. - kind : {'quicksort', 'mergesort', 'heapsort', 'timsort', 'stable'}, optional - Sorting algorithm. Default is 'quicksort'. + kind : {'quicksort', 'mergesort', 'heapsort', 'stable'}, optional + Sorting algorithm. The default is 'quicksort'. Note that both 'stable' + and 'mergesort' use timsort under the covers and, in general, the + actual implementation will vary with datatype. The 'mergesort' option + is retained for backwards compatibility. + + .. versionchanged:: 1.17.0. + The 'stable' option was added together with stable sorting + algorithms other than 'mergesort'. + order : str or list of str, optional When `a` is an array with fields defined, this argument specifies which fields to compare first, second, etc. A single field can @@ -855,18 +863,22 @@ def sort(a, axis=-1, kind='quicksort', order=None): The various sorting algorithms are characterized by their average speed, worst case performance, work space size, and whether they are stable. A stable sort keeps items with the same key in the same relative - order. The four available algorithms have the following + order. The four algorithms implemented in NumPy have the following properties: =========== ======= ============= ============ ======== kind speed worst case work space stable =========== ======= ============= ============ ======== 'quicksort' 1 O(n^2) 0 no - 'mergesort' 2 O(n*log(n)) ~n/2 yes 'heapsort' 3 O(n*log(n)) 0 no + 'mergesort' 2 O(n*log(n)) ~n/2 yes 'timsort' 2 O(n*log(n)) ~n/2 yes =========== ======= ============= ============ ======== + .. note:: The datatype determines which of 'mergesort' or 'timsort' + is actually used, even if 'mergesort' is specified. User selection + at a finer scale is not currently available. + All the sort algorithms make temporary copies of the data when sorting along any but the last axis. Consequently, sorting along the last axis is faster and uses less space than sorting along @@ -895,7 +907,10 @@ def sort(a, axis=-1, kind='quicksort', order=None): worst case O(n*log(n)). 'stable' automatically choses the best stable sorting algorithm - for the data type being sorted. It is currently mapped to timsort. + for the data type being sorted. It, along with 'mergesort' is + currently mapped to timsort. API forward compatibility currently limits the + ability to select the implementation and it is hardwired for the different + data types. .. versionadded:: 1.17.0 Timsort is added for better performance on already or nearly @@ -967,8 +982,16 @@ def argsort(a, axis=-1, kind='quicksort', order=None): axis : int or None, optional Axis along which to sort. The default is -1 (the last axis). If None, the flattened array is used. - kind : {'quicksort', 'mergesort', 'heapsort', 'timsort', 'stable'}, optional - Sorting algorithm. + kind : {'quicksort', 'mergesort', 'heapsort', 'stable'}, optional + Sorting algorithm. The default is 'quicksort'. Note that both 'stable' + and 'mergesort' use timsort under the covers and, in general, the + actual implementation will vary with datatype. The 'mergesort' option + is retained for backwards compatibility. + + .. versionchanged:: 1.17.0. + The 'stable' option was added together with stable sorting + algorithms other than 'mergesort'. + order : str or list of str, optional When `a` is an array with fields defined, this argument specifies which fields to compare first, second, etc. A single field can |