运行图减小了矩阵的维数 [英] Running Map reduces the dimensions of the matrices

问题描述

说我有三个列表:

 l_zero
[[1]]
     [,1] [,2]
[1,]    0    0
[2,]    0    0

[[2]]
     [,1] [,2]
[1,]    0    0
[2,]    0    0

l_ind <- list(matrix(c(1,1), ncol = 2), matrix(c(1,1,1,2), ncol = 2))
l_ind
[[1]]
     [,1] [,2]
[1,]    1    1

[[2]]
     [,1] [,2]
[1,]    1    1
[2,]    1    2

l_val <- list(5, c(4, 7))
l_val
[[1]]
[1] 5

[[2]]
[1] 4 7

我想在三个列表上运行Map，目标是在l_zero中用l_val中的值替换l_ind中的坐标零. 我的尝试给了我以下信息:

I would like to run Map over the three lists with the goal of replacing in l_zero the zeros with the coordinates in l_ind with the values from l_val. My attempt gives me the following:

Map(function(l_zero, l_ind, l_val) l_zero[l_ind] <- l_val, l_zero = l_zero, l_ind = l_ind, l_val = l_val)
[[1]]
[1] 5

[[2]]
[1] 4 7

如您所见，矩阵的原始尺寸减小了，但是我想保留矩阵的尺寸，只是将值替换为l_ind中的坐标.我尝试了l_zero[l_ind, drop = FALSE]，但这也无济于事.

As you can see, the original dimensions of the matrices are reduced, but I would like to keep the dimensions of the matrices and just replace the values with the coordinates in l_ind. I tried l_zero[l_ind, drop = FALSE], but that didn't help either.

有人可以帮我吗?

推荐答案

这里有一个更简单的方法，[<-替换函数可以在Map()的function参数中使用.按顺序需要三个参数.

Here's a bit simpler method, The [<- replacement function can be used in Map()'s function argument. It takes three arguments, in order.

Map("[<-", l_zero, l_ind, l_val)
# [[1]]
#      [,1] [,2]
# [1,]    5    0
# [2,]    0    0
# 
# [[2]]
#      [,1] [,2]
# [1,]    4    7
# [2,]    0    0

这篇关于运行图减小了矩阵的维数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！