Matlab中的简单滑动窗口过滤器 [英] simple sliding window filter in Matlab

问题描述

我没有 nlfilter 的包，我也不太了解 这个例子.

I don't have the package for nlfilter and I didn't quite follow this example.

我有一个非常简单的函数 fun 并且我想将它应用到数组的移动窗口.数组是 Nx1，我想查看长度 k 间隔，比如说.所以对于 N=10 和 k=3 和 fun = @(x) min(x); 我会得到

I have a really simple function fun and I want to apply it to a moving window of an array. The array is Nx1, and I want to look at length k intervals, say. So for N=10 and k=3 and fun = @(x) min(x); I would get

A = [13 14 2 14 10 3 5 9 15 8];

filter(A,k,fun) = [2 2 2 3 3 3 5 8];

这里我只想查看索引 1,2,3 然后是 2,3,4 然后...然后是 8,9,10，所以最终序列的长度是 7.我可以用 for 循环轻松做到这一点，但我不知道如何为 Matlab 向量化它.请帮忙.谢谢.

Here I only want to look at indices 1,2,3 then 2,3,4 then ... then 8,9,10, so the final sequence is length 7. I can do this easy with a for loop, but I have no idea how to vectorize it for Matlab. Help, please. Thanks.

推荐答案

这是一种非常简单快捷的方法:

Here is one very simple and fast way to do it:

>> min([A(1:(end-2)); A(2:(end-1)); A(3:end)], [], 1)

ans =

     2     2     2     3     3     3     5     8

因为你想要一个完整的功能......

Since you want a full function...

function running_min = running_min(x, k)

xrep = repmat(x, 1, k);
xrep = reshape([xrep zeros(1, k)], length(x)+1, k);
running_min = min(xrep, [], 2)';
running_min = running_min(1:end-k);

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