numpy.ma.argsort

numpy.ma.argsort(a, axis=None, kind='quicksort', order=None, fill_value=None)

Return an ndarray of indices that sort the array along the specified axis. Masked values are filled beforehand to fill_value.

Parameters :

axis : int, optional

Axis along which to sort. The default is -1 (last axis). If None, the flattened array is used.

fill_value : var, optional

Value used to fill the array before sorting. The default is the fill_value attribute of the input array.

kind : {‘quicksort’, ‘mergesort’, ‘heapsort’}, optional

Sorting algorithm.

order : list, optional

When a is an array with fields defined, this argument specifies which fields to compare first, second, etc. Not all fields need be specified.

Returns :

index_array : ndarray, int

Array of indices that sort a along the specified axis. In other words, a[index_array] yields a sorted a.

See also

sort

Describes sorting algorithms used.

lexsort

Indirect stable sort with multiple keys.

ndarray.sort

Inplace sort.

Notes

See sort for notes on the different sorting algorithms.

Examples

>>> a = np.ma.array([3,2,1], mask=[False, False, True])
>>> a
masked_array(data = [3 2 --],
             mask = [False False  True],
       fill_value = 999999)
>>> a.argsort()
array([1, 0, 2])