R循环功能怎么了？

Question

I am trying to run a loop function like this:

x <- c(1,2,3,4,7,8,9,10,13,14,15,16,19,20,22,23,24,26) 
n<-rep(NA,length(x))
for (ii in 1:length(x)){
  n[ii]<-subset(dat1, Plot==ii)
}

However, error message appeared:

There were 18 warnings (use warnings() to see them)

The outputs that I am looking for is 18 individual data n1,n2,n3,n4,n7,...n24&n26 subset from main data dat1 .

Answer 1

I'm having a little trouble understanding what you want to do, but if you have a vector dat1 , and you want to form a new vector n that contains the 1st, 2nd, ..., 26th elements of dat1 , that's pretty easy to do in R. Try:

> dat1 <- 1:60
> x <- c(1,2,3,4,7,8,9,10,13,14,15,16,19,20,22,23,24,26)
> n <- dat1[x]
> n
 [1]  1  2  3  4  7  8  9 10 13 14 15 16 19 20 22 23 24 26

Answer 2

If what you're trying to do is create a "vector" of data.frames, each one corresponding to a certain level of your Plot variable, you should be using a list , not a vector .

x <- c(1,2,3,4,7,8,9,10,13,14,15,16,19,20,22,23,24,26) 
n <- list()
length(n) <- length(x)

for (ii in 1:length(x)){
  n[[ii]] <- subset(dat1, Plot==ii)
}