数组中最大值和最小值的索引

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 max 和 min 可以将argmax和argmin作为第二个参数返回.
值得一提的是，您可以使用特定尺寸的这些功能:

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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