Odp: Question about collapse/aggregate and avoidance of loops
Hi r-help-bounces at r-project.org napsal dne 29.01.2009 07:52:37:
Dear all,
given the following data
## original data
id <- c(1,1,1,2,2,3)
author <- c("A","B","C","D","E","F")
tmp <- data.frame(id,author)
tmp
> tmp
id author 1 1 A 2 1 B 3 1 C 4 2 D 5 2 E 6 3 F What is the best (most efficient/vectorized/avoiding loops) approach to obtain the following data frame? id author 1 "A, B, C" 2 "D, E" 3 "F"
Not sure if it is most efficient but aggregate(tmp$author, list(tmp$id), function(x) paste(x, collapse=",")) can do the trick Regards Petr
Thanks for your help, Bernd
> version
_ platform i386-pc-mingw32 arch i386 os mingw32 system i386, mingw32 status Patched major 2 minor 8.1 year 2008 month 12 day 22 svn rev 47296 language R version.string R version 2.8.1 Patched (2008-12-22 r47296)
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