复制向量并将每个副本向下移动 1 行，无需 for 循环 [英] Replicate vector and shift each copy by 1 row down without for-loop

问题描述

我想复制一个向量 N 次来创建一个矩阵，每个副本向下移动 1 行.请参见图像(第一列是向量 1 到 5).如果不用 for 循环也能实现，那就太好了.

I would like replicate a vector N times to create a matrix with each copy shifted 1 row down. See image (first column is the vector 1 to 5). It would be great if this can be achieved without using for loop.

到目前为止能够做到这一点 repmat(my_vector, 1, 5) 来创建一个 N x 5 矩阵.

So far was able to to do this repmat(my_vector, 1, 5) to create an N x 5 matrix.

推荐答案

您可以使用 toeplitz 和 tril;

a = [1 2 3 4 5]
out = tril( toeplitz(a) )

或

out = toeplitz(a, a*0)
%// out = toeplitz(a, zeros(size(a)) )  %// for large arrays

或者如果你不介意一些快乐的翻转:

or if you don't mind some happy flipping:

out = flipud( hankel( flipud(a(:)) ) )

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