Python 获取多维numpy数组中最大项的位置
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原文地址: http://stackoverflow.com/questions/3584243/
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Get the position of the biggest item in a multi-dimensional numpy array
提问by kame
How can I get get the position of the biggest item in a multi-dimensional numpy array?
如何获得多维numpy数组中最大项目的位置？
采纳答案by Manoj Govindan
The argmax()method should help.
该argmax()方法应该有所帮助。
Update
更新
(After reading comment) I believe the argmax()method would work for multi dimensional arrays as well. The linked documentation gives an example of this:
（阅读评论后）我相信该argmax()方法也适用于多维数组。链接的文档给出了一个例子：
>>> a = array([[10,50,30],[60,20,40]])
>>> maxindex = a.argmax()
>>> maxindex
3
Update 2
更新 2
(Thanks to KennyTM's comment) You can use unravel_index(a.argmax(), a.shape)to get the index as a tuple:
（感谢KennyTM的评论）您可以使用unravel_index(a.argmax(), a.shape)将索引作为元组获取：
>>> from numpy import unravel_index
>>> unravel_index(a.argmax(), a.shape)
(1, 0)
回答by otterb
(edit) I was referring to an old answer which had been deleted. And the accepted answer came after mine. I agree that argmaxis better than my answer.
（编辑）我指的是一个已删除的旧答案。接受的答案是在我之后。我同意这argmax比我的答案更好。
Wouldn't it be more readable/intuitive to do like this?
这样做不是更易读/更直观吗？
numpy.nonzero(a.max() == a)
(array([1]), array([0]))
Or,
或者，
numpy.argwhere(a.max() == a)
回答by iFederx
You can simply write a function (that works only in 2d):
您可以简单地编写一个函数（仅适用于 2d）：
def argmax_2d(matrix):
maxN = np.argmax(matrix)
(xD,yD) = matrix.shape
if maxN >= xD:
x = maxN//xD
y = maxN % xD
else:
y = maxN
x = 0
return (x,y)
