numpy.argsort(a, axis=-1, kind='quicksort', order=None)
[source]
Returns the indices that would sort an array.
Perform an indirect sort along the given axis using the algorithm specified by the kind
keyword. It returns an array of indices of the same shape as a
that index data along the given axis in sorted order.
Parameters: |
a : array_like Array to sort. 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’}, optional Sorting algorithm. order : str or list of str, optional When |
---|---|
Returns: |
index_array : ndarray, int Array of indices that sort |
See also
sort
lexsort
ndarray.sort
argpartition
See sort
for notes on the different sorting algorithms.
As of NumPy 1.4.0 argsort
works with real/complex arrays containing nan values. The enhanced sort order is documented in sort
.
One dimensional array:
>>> x = np.array([3, 1, 2]) >>> np.argsort(x) array([1, 2, 0])
Two-dimensional array:
>>> x = np.array([[0, 3], [2, 2]]) >>> x array([[0, 3], [2, 2]])
>>> np.argsort(x, axis=0) array([[0, 1], [1, 0]])
>>> np.argsort(x, axis=1) array([[0, 1], [0, 1]])
Sorting with keys:
>>> x = np.array([(1, 0), (0, 1)], dtype=[('x', '<i4'), ('y', '<i4')]) >>> x array([(1, 0), (0, 1)], dtype=[('x', '<i4'), ('y', '<i4')])
>>> np.argsort(x, order=('x','y')) array([1, 0])
>>> np.argsort(x, order=('y','x')) array([0, 1])
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https://docs.scipy.org/doc/numpy-1.13.0/reference/generated/numpy.argsort.html