[R] Conditionally swap items in a data frame

[Mark Leeds]

temp<-df1$a
df$a<-ifelse(df1$c == 2, df$b, df$a)
df$b<-ifelse(df1$c == 2, temp, df$b)


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of Michael Kubovy
Sent: Thursday, April 17, 2008 10:53 AM
To: r-help at stat.math.ethz.ch
Subject: [R] Conditionally swap items in a data frame

df1 <- data.frame(a = LETTERS[1:2], b = LETTERS[3:4], c = 1:2)

I am looking for an idiom that swaps the elements of df$a and df$b  
when (e.g.) df$c == 2, resulting in

df2 <- data.frame(a = LETTERS[c(1, 4)], b = LETTERS[c(3, 2)], c = 1:2)
_____________________________
Professor Michael Kubovy
University of Virginia
Department of Psychology
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