R help - Nov 2008 - How to split DF into a list and avoid NULL elements in this list

Hello,

I'm trying to split my DF into a list using incremental loop. How can
I avoid NULL elements in this list?

DF <- data.frame(var1 = 1:10, var2 = 11:20, var3 = 21:30, var4 = 31:40)

x <- list()
i <- 1
while (i <= ncol(DF)-1) {
          x[[i]] <- DF[, i:c(i+1)]
          i <- i + 2
}
x

Many thanks,
Lauri

Here's one way

x <- sapply(seq(1,ncol(DF),by=2), function(i) DF[,i:(i+1)], simplify=F) 

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Lauri Nikkinen
Sent: Tuesday, November 25, 2008 9:00 AM
To: r-help at stat.math.ethz.ch
Subject: [R] How to split DF into a list and avoid NULL elements in this
list

Hello,

I'm trying to split my DF into a list using incremental loop. How can I
avoid NULL elements in this list?

DF <- data.frame(var1 = 1:10, var2 = 11:20, var3 = 21:30, var4 = 31:40)

x <- list()
i <- 1
while (i <= ncol(DF)-1) {
          x[[i]] <- DF[, i:c(i+1)]
          i <- i + 2
}
x

Many thanks,
Lauri

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