数组中最大值和最小值的索引 [英] Index of max and min value in an array

问题描述

如何在不循环的情况下找到数组中最大元素的索引?

How can I find the index of the maximum element in an array without looping?

例如，如果我有:

a = [1 2 999 3];

我想定义一个函数indexMax，以便indexMax(a)返回3.

I want to define a function indexMax so that indexMax(a) would return 3.

同样，用于定义indexMin.

推荐答案

Evgeni

As pointed by Evgeni max and min can return the argmax and argmin as second arguments.
It is worth while noting that you can use these functions along specific dimensions:

 A = rand(4); % 4x4 matrix
 [ row_max row_argmax ] = max( A, [], 2 ); % max for each row - 2nd dimension
 [ col_min col_argmin ] = min( A, [], 1 ); % min for each column - 1st dimension

请注意第二个空的[]参数-至关重要的是max( A, [], 2 )根本不等于 (我将作为一个小练习，留给您看一下max( A, 2 )确实).

Note the empty [] second argument - it is crucial max( A, [], 2 ) is not at all equivalent to max( A, 2 ) (I'll leave it to you as a small exercise to see what max( A, 2 ) does).

这些沿维度"调用返回的argmax/argmin是行/列索引.

The argmax/argmin returned from these "along dimension" calls are row/col indices.

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