R，遍历矩阵的行向量 [英] R, iterating over the row vectors of a matrix

问题描述

我有一些向量vect，我想遍历矩阵的行向量v并计算:

I have some vector vect and I want to iterate over the row vectors vof a matrix and calculate:

cov(v, vect).

我尝试过:

for(vect in mat2)     #where mat2 is a 215 by 31 matrix

但是，每个向量似乎都是一个值为1的标量.

However, each vector appeared to be a scalar with value 1.

1. 如何迭代矩阵的行向量?
2. 为了使这个更好，因为我有兴趣计算cov(v, vect)的和，其中v是行向量，我该如何使用高阶函数left-fold和right-fold

1. How do I iterate over the row vectors of a matrix?
2. To make this even better, since I am interested in calculating the sum of cov(v, vect) where v is a row vector, how can I use the higher-order functions left-fold and right-fold

推荐答案

您在寻找apply吗?

apply(mat2, 1, function(v)cov(v,vect))

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