On Tue, Feb 24, 2009 at 3:10 PM, Sean Zhang wrote:
> ...Want to delete many variables in a dataframe....
> df<-data.frame(var.a=rnorm(10), var.b=rnorm(10),var.c=rnorm(10))
> df[,'var.a']<-NULL #this works for one single variable
> df[,c('var.a','var.b')]<-NULL #does not work for multiple variables
Actually, setting to NULL works fine for multiple variables, but you
need one NULL per variable:
> df[,c("var.a","var.b")] <- list(NULL,NULL)
> df
var.c
1 1.2470314
2 -0.7075917
3 -1.3959612
If the variable list is in a variable:
> vars <- c("var.a","var.c")
Careful, rep requires a *list* of NULL, not an element:
> df[,vars] <- rep(list(NULL),length(vars))
Hope this helps,
-s
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
