[R] Several factors same levels

[Dimitris Rizopoulos]

one way is the following:

DF <- data.frame(id = 1:6,
     sex = gl(2, 3, labels = c("M", "F")),
     x = sample(0:1, 6, TRUE), y = sample(0:1, 6, TRUE),
     z = rnorm(6))

f <- function (x) {
     if (all(unique(x) %in% 0:1))
         factor(x, levels = 0:1, labels = c("No", "Yes"))
     else
         x
}

DF[] <- lapply(DF, f)


I hope it helps.

Best,
Dimitris


On 4/19/2011 10:57 AM, dereksloan wrote:
> This is probably very simple but I'm new to R so apologies for being stupid.
>
> I have some data with No coded as 0 and yes coded as 1.
>
> e.g.
>
> id sex alcohol smoker
> 1   M     0        1
> 2   F      1        0
> 3   M     0        0
>
> I realise I can covert the numerical variable back to a factor by
>
> falcohol<-factor(alcohol,levels=0:1)
> levels<-c("No","Yes")
> fsmoker<-factor(smoker,levels=0:1)
> levels<-c("No","Yes")
>
> but can I do this for all factors using the same levels in a single command
> to make it easier (i.e. switch all 0/1, no/yes variables without having to
> recode the same factor levels for them all)?
>
> Derek
>
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-- 
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center

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