如何沿一个轴获取numpy数组中最大元素的索引

I have a 2 dimensional NumPy array. I know how to get the maximum values over axes:

我有一个2维NumPy数组。我知道如何获得轴上的最大值：

>>> a = array([[1,2,3],[4,3,1]])
>>> amax(a,axis=0)
array([4, 3, 3])

How can I get the indices of the maximum elements? So I would like as output array([1,1,0])

如何获得最大元素的索引？所以我想作为输出数组（[1,1,0]）

4 个解决方案

>>> a.argmax(axis=0)

array([1, 1, 0])

>>> import numpy as np
>>> a = np.array([[1,2,3],[4,3,1]])
>>> i,j = np.unravel_index(a.argmax(), a.shape)
>>> a[i,j]
4

argmax（）只返回每行的第一个匹配项。 http://docs.scipy.org/doc/numpy/reference/generated/numpy.argmax.html

If you ever need to do this for a shaped array, this works better than unravel:

如果你需要为一个异形数组做这个，这比解开更好：

import numpy as np
a = np.array([[1,2,3], [4,3,1]])  # Can be of any shape
indices = np.where(a == a.max())

You can also change your conditions:

您还可以更改条件：

indices = np.where(a >= 1.5)

The above gives you results in the form that you asked for. Alternatively, you can convert to a list of x,y coordinates by:

以上以您要求的形式提供结果。或者，您可以通过以下方式转换为x，y坐标列表：

x_y_coords =  zip(indices[0], indices[1])

v = alli.max()
index = alli.argmax()
x, y = index/8, index%8

>>> a.argmax(axis=0)

array([1, 1, 0])

>>> import numpy as np
>>> a = np.array([[1,2,3],[4,3,1]])
>>> i,j = np.unravel_index(a.argmax(), a.shape)
>>> a[i,j]
4