>>> import numpy

>>> help(numpy.argsort)

Help on function argsort in module numpy.core.fromnumeric:

argsort(a, axis=-1, kind='quicksort', order=None)

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.

 

从中可以看出argsort函数返回的是数组值从小到大的索引值

 

Examples

--------

One dimensional array:一维数组

>>> x = np.array([3, 1, 2])

>>> np.argsort(x)

array([1, 2, 0])

Two-dimensional array:二维数组

>>> x = np.array([[0, 3], [2, 2]])

>>> x

array([[0, 3],

[2, 2]])

>>> np.argsort(x, axis=0) #按列排序

array([[0, 1],

[1, 0]])

>>> np.argsort(x, axis=1) #按行排序

array([[0, 1],

[0, 1]])

 

#######################################

 

例1：

 

>>> x = np.array([3, 1, 2])

>>> np.argsort(x) #按升序排列

array([1, 2, 0])

>>> np.argsort(-x) #按降序排列

array([0, 2, 1])

 

>>> x[np.argsort(x)] #通过索引值排序后的数组

array([1, 2, 3])

>>> x[np.argsort(-x)]

array([3, 2, 1])

 

另一种方式实现按降序排序：

 

>>> a = x[np.argsort(x)]

>>> a

array([1, 2, 3])

>>> a[::-1]

array([3, 2, 1])