是否有随机洗牌在MATLAB矩阵更好​​/更快的方法？ [英] Is there a better/faster way of randomly shuffling a matrix in MATLAB?

问题描述

在MATLAB中，我使用shake.m功能（<一个href=\"http://www.mathworks.com/matlabcentral/fileexchange/10067-shake\">http://www.mathworks.com/matlabcentral/fileexchange/10067-shake)随机洗牌每一列，例如：

In MATLAB, I am using the shake.m function (http://www.mathworks.com/matlabcentral/fileexchange/10067-shake) to randomly shuffle each column. For example:

a = [1 2 3; 4 5 6; 7 8 9]
a =

     1     2     3
     4     5     6
     7     8     9

b = shake(a)
b =

     7     8     6
     1     5     9
     4     2     3

此功能不正是我想要的，但我列的非常的长（> 10,000,000），因此这需要很长时间才能运行。有谁知道实现这一目标的一个更快的方法？我试图分别摇动每个列向量但这不是更快。谢谢！

This function does exactly what I want, however my columns are very long (>10,000,000) and so this takes a long time to run. Does anyone know of a faster way of achieving this? I have tried shaking each column vector separately but this isn't faster. Thanks!

推荐答案

下面是一个简单的量化方法。请注意，它创建了一个辅助的基质（ IND ）的大小相同 A ，所以这取决于你的记忆可能可用与否。

Here's a simple vectorized approach. Note that it creates an auxiliary matrix (ind) the same size as a, so depending on your memory it may be usable or not.

[~, ind] = sort(rand(size(a))); %// create a random sorting for each column
b = a(bsxfun(@plus, ind, 0:size(a,1):numel(a)-1)); %// convert to linear index

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