numpy.argsort
numpy.argsort(a, axis=-1, kind=’quicksort’, order=None)
Returns the indices that would sort an array.
返回排序数组的索引。
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.
使用kind关键字指定的算法沿给定轴进行间接排序。 它按照排序的顺序返回与给定轴的索引数据相同形状的索引数组。
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 a is an array with fields defined, this argument specifies which fields to compare first, second, etc. A single field can be specified as a string, and not all fields need be specified, but unspecified fields will still be used, in the order in which they come up in the dtype, to break ties.
Returns:
index_array : ndarray, int
Array of indices that sort a along the specified axis. If a is one-dimensional, a[index_array] yields a sorted a.
Examples
One dimensional array:
返回的结果为 输入数组 元素从小到大 的索引
>>> 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]])
