通过使用循环功能删除矩阵的k个第一行 [英] Drop k first rows of a matrix by using loop function

问题描述

我创建了一个名为col的尺寸为150x4的矩阵.

I have created a matrix called col of dimension 150x4.

现在，我想通过绑定(col，col1，....，col149)创建一个150x600的矩阵，其中colk是通过将col的前k行替换为零来创建的.

Now I want to create a 150x600 matrix by binding (col,col1,....,col149), where colk is created by replacing the first k rows of col by zeros.

我的col1代码是

c1<-col[-1,] row<-(0,0,0,0) col1<-rbind(row,c1)

c1<-col[-1,] row<-(0,0,0,0) col1<-rbind(row,c1)

但是，如果k = 149，这将非常困难.我猜需要一个循环功能.另外，我创建的col1看起来不像矩阵.当我在R中打印时，没有行号.

However, It will be really hard if If k=149. I guess a loop function is required. Also, col1 that I created doesn't look like a matrix. When I print it in R, there's no row numbers.

由于我是R语言的新手，所以不知道如何在R语言中做这些事情.

Since I am new to R, don't know how to do these things in R.

我的col代码是col< -t(res)，可以在 如何从给定向量，使用for循环

My code for col is col<-t(res),which can be seen in How to make a matrix from a given vector by using for loop

有人可以帮我解决这个问题吗?提前致谢 ！

Can anyone help me address this issue? Thanks in advance !

推荐答案

可能有帮助:

res1 <-  cbind(colN,do.call(`cbind`, lapply(1:149, function(i) {
                        rN <- matrix(rowN[col(colN[1:i,,drop=FALSE])], ncol=4)
                        rbind(rN, colN[-(1:i),]) 
                       })))

  dim(res1)
 #[1] 150 600

数据

通过链接

data

From the link

set.seed(25)
x<-runif(150,-2,2)
x1<-c(0,0,0,0,x)
n <- length(x1)-1
res <- sapply((4:n)-3, function(i) x1[(i+3):i])
colN <- t(res)
rowN <- rep(0,4)

这篇关于通过使用循环功能删除矩阵的k个第一行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！