Matlab相当于Numpy广播? [英] Matlab equivalent of Numpy broadcasting?

问题描述

我正在尝试找到一种方法，从Matlab中3 *(大量)矩阵的每一列中减去3号矢量.当然，我可以使用循环，但是我正在尝试找到一些更有效的解决方案，有点像numpy广播.哦，我不能使用repmat，因为我没有足够的内存来使用它(因为它创建了另一个3 *(大数字)矩阵)...

这可能吗?

解决方案

由于 bsxfun 可能会解决问题但是，根据我的经验，它通常也有内存问题，但少于repmat.

因此语法为:

AA = bsxfun(@minus,A,b)，其中b是向量，A是您的大矩阵

但是，我恳请您介绍有毛病的版本，然后再决定！很可能由于内存限制，您可能没有选择:)

I'm trying to find some way to substract a size 3 vector from each column of a 3*(a big number) matrix in Matlab. Of course I could use a loop, but I'm trying to find some more efficient solution, a bit like numpy broadcasting. Oh, and I can't use repmat because I just don't have enough memory to use it (as it creates yet another 3*(a big number) matrix)...

Is this possible?

解决方案

Loops aren't bad in MATLAB anymore thanks to compiler optimizations like just-in-time acceleration (JITA). etc. Most of the time, I've noticed that a solution with loops in current MATLAB versions is much faster than complicated (albeit, cool :D) one-liners.

bsxfun might do the trick but in my experience, it tends to have memory issues as well but less so than repmat.

So the syntax would be:

AA = bsxfun(@minus,A,b) where b is the vector and A is your big matrix

But I urge you to profile the loopy version and then decide! Most probably, due to memory constraints, you might not have a choice :)

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