How can I select columns from a dataframe in a function? [duplicate]

Question

There is a dataframe (x) with large number of columns. I want to select columns from it inside a function.

selectcols<-function(dat,xvar,yvar){
  t<-dat[,c(xvar,yvar)] 
}

selectcols(dat=x,xvar = "area",yvar = "y")

Here y and area are two columns. But this is not working. How can I fix it?

I thiink you don't need a function to select columns. Unless you want to add some criteria with which some columns will be selected. Have a look at this df <-data.frame(a=1:5,b=6:10,c=40:44). df[,c("a","c")] — DJJ
– DJJ, Commented Aug 27, 2015 at 20:37
It's a part of a bigger codebase. And I need to do this inside a function. — maximusdooku
– maximusdooku, Commented Aug 27, 2015 at 20:37
This should work: selectcols <- function(d,jx,jy) "["(d,c(jx,jy)) — Frank
– Frank, Commented Aug 27, 2015 at 20:42
@darwin not necessarily. @maximusdooku Just end your function with t or return(t) . That should to the job. — DJJ
– DJJ, Commented Aug 27, 2015 at 20:42

Michael Bellhouse · Accepted Answer · 2015-08-28 00:48:05Z

0

I like using dplyr for this

library(dplyr)
selectcols <- function(dat,xvar,yvar){
  t <- dat %>% select(matches(xvar), matches(yvar))
}

x <- data.frame(area = 1:10, y = 11:20, z = LETTERS[1:10])
selection <- selectcols(dat=x, xvar = "area", yvar = "y")

answered Aug 28, 2015 at 0:48

Michael Bellhouse

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