我甚至不知道如何描述我想做什么，所以希望这个标题至少有一些意义.
如果我向您展示:
我有一个简单的字母a到e的3x5矩阵:
matrix(data = rep(letters[1:5], 3), nrow = 3, ncol = 5, byrow = TRUE)
它给出了:
[,1] [,2] [,3] [,4] [,5]
[1,] "a" "b" "c" "d" "e"
[2,] "a" "b" "c" "d" "e"
[3,] "a" "b" "c" "d" "e"
我想在不手动键入的情况下将其更改为:
[,1] [,2] [,3] [,4] [,5]
[1,] "a" "b" "c" "d" "e"
[2,] "e" "a" "b" "c" "d"
[3,] "d" "e" "a" "b" "c"
我在考虑某种循环系统或类似的系统，但我不知道从哪里开始.
对于简单的情况，您可以try 这个for循环.
n <- dim(m3)[2]
for (i in seq_len(nrow(m))[-1]) {
m3[i, ] <- c(m3[i, (n - i + 2):n], m3[i, 1:(n - i + 1)])
}
m3
# [,1] [,2] [,3] [,4] [,5]
# [1,] "a" "b" "c" "d" "e"
# [2,] "e" "a" "b" "c" "d"
# [3,] "d" "e" "a" "b" "c"
为了让模式在更长的矩阵中重复，我们可以概括如下:
n <- dim(m7)[2]
for (i in seq_len(nrow(m7))[-1]) {
j <- i %% 5
if (j == 0) j <- 5
if (j > 1) m7[i, ] <- c(m7[i, (n - j + 2):n], m7[i, 1:(n - j + 1)])
}
m7
# [,1] [,2] [,3] [,4] [,5]
# [1,] "a" "b" "c" "d" "e"
# [2,] "e" "a" "b" "c" "d"
# [3,] "d" "e" "a" "b" "c"
# [4,] "c" "d" "e" "a" "b"
# [5,] "b" "c" "d" "e" "a"
# [6,] "a" "b" "c" "d" "e"
# [7,] "e" "a" "b" "c" "d"
Data:
m3 <- matrix(data=letters[1:5], nrow=3, ncol=5, byrow=TRUE)
m7 <- matrix(data=letters[1:5], nrow=7, ncol=5, byrow=TRUE)