Methods for ndarray

Methods for ndarray

 

 

Use help in Python

>>> Import numpy
>>> Help (numpy. argsort)

 

Argsort function usage: (numpy-ref-1.8.1P1240)

Argsort (a, axis =-1, kind = 'quicksort ', order = None)
Returns the indices that wowould sort an array.

The argsort function returns an index value from small to large.

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Examples
--------
One dimen1_array: One-dimensional array
>>> X = np. array ([3, 1, 2])
>>> Np. argsort (x)
Array ([1, 2, 0])

Two-dimen1_array: Two-dimensional array
>>> X = np. array ([[0, 3], [2, 2])
>>> X
Array ([[0, 3],
[2, 2])
>>> Np. argsort (x, axis = 0) # sort by Column
Array ([[0, 1],
[1, 0])
>>> Np. argsort (x, axis = 1) # sort by row
Array ([[0, 1],
[0, 1])

>>> X = np. array ([3, 1, 2])
>>> Np. argsort (x) # sort in ascending order
Array ([1, 2, 0])
>>> Np. argsort (-x) # sort by descending order
Array ([0, 2, 1])

Another method is to sort data in descending order:

>>> A = x [np. argsort (x)]
>>>
Array ([1, 2, 3])
>>> A [:-1]
Array ([3, 2, 1])

>>> X [np. argsort (x)] # array sorted by index value
Array ([1, 2, 3])
>>> X [np. argsort (-x)]
Array ([3, 2, 1])

From: http://blog.csdn.net/pipisorry/article/details/41214819

Ref:

Argsort function usage in numpy