Python numpy保留已排序的2D数组的索引列表

I have a 2D numpy array and I want to create a new 1D array where it is indices of numbers in the first array if they are sorted in an ascending order. For the following array:

我有一个2D numpy数组,我想创建一个新的1D数组,如果它们按升序排序,它是第一个数组中的数字索引。对于以下数组:

A = [[1,0,2],
     [0,3,0]]

I want this to be like:

我想要这样:

B = [[1,1],[0,2],[0,0],[0,1],[1,0],[1,2]]

Any idea how it can be done in python using predefined functions?

知道如何使用预定义函数在python中完成它吗?

Thanks

1 个解决方案

#1

You can use argsort to sort the indices of flattened array, followed by unravel_index to convert the flat index back to coordinates:

您可以使用argsort对flattened数组的索引进行排序,然后使用unravel_index将flat index转换回坐标:

>>> i = (-a).argsort(axis=None, kind='mergesort')
>>> j = np.unravel_index(i, a.shape) 
>>> np.vstack(j).T
array([[1, 1],
       [0, 2],
       [0, 0],
       [0, 1],
       [1, 0],
       [1, 2]])

-a and kind='mergesort' is in order to sort the array in a stable manner in descending order (to match the output you are looking for).

-a和kind ='mergesort'是为了按降序顺序对数组进行排序(以匹配您要查找的输出)。

If you do not care about having a stable sort, replace the first line with:

如果您不关心稳定排序,请将第一行替换为:

>>> i = a.argsort(axis=None)[::-1]

#1