[R] first occurrence of a value?

From: Albert-Jan Roskam <fomcl_at_yahoo.com>
Date: Wed, 04 May 2011 04:52:07 -0700 (PDT)


Hello,

A simple question perhaps, but how do I, within each row, find the first occurence of the number 1 in the df below? I want to use this position to programmatically create the variable 'year'. I'v come up with a solution, but I find it downright ugly. Is there a simpler way? I was hoping for a useful built-in function that I don;t yet know about.

df <- data.frame(j1999=c(0,0,0,0,1,0), j2000=c(NA, 1, 1, 1, 0, 0), j2001=c(1, 0, 1, 0, 0, 0), year=c(2001, 2000, 2000, 2000, 1999, NA)) library(gsubfn)
x <- apply(df==1, 1, which)
giveYear <- function(df) { return( as.numeric(gsubfn("^[^0-9]+", "", names(df)[1])) ) }
df$year2 <- sapply(x, giveYear)

Thanks in advance!

 Cheers!!
Albert-Jan



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