[R] making a dataframe out of lapply() result

Roger Peng rpeng at stat.ucla.edu
Tue Apr 15 20:42:27 CEST 2003


You could try:

s <- lapply(tester.L, function(x) x <- x[1,] )
do.call("rbind", s)

-roger
_______________________________
UCLA Department of Statistics
http://www.stat.ucla.edu/~rpeng

On Tue, 15 Apr 2003, Remko Duursma wrote:

> Dear R-helpers,
> 
> i have a question on how to vectorize this problem:
> 
> i have a dataframe:
> 
> tester <- data.frame(groups=c("A","A","B","B","C","C"), one=c(1,1,2,2,3,3), two=c(6,6,7,7,8,8))
> 
> # i split it into a list
> tester.L <- split(tester, tester$groups)
> 
> # And want to keep only the first item in each:
> lapply(tester.L, function(x) x <- x[1,] )
> 
> 
> How do i make a dataframe out of the last result, which looks like
> "tester", without looping? (i can use rbind in a for loop, but is
> rather slow)
> 
> thanks for your help,
> 
> Remko Duursma
> 
> 
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