[R] Translate the elements of a dataframe

[Chuck Cleland]

On 4/16/2009 2:58 PM, Juergen Rose wrote:
> The second beginner question. I want to create a new dataframe, where
> each element of the original dataframe is translated to 1 if it was "+",
> to 0 if it was "-" to -1 otherwise. I could do with:
> 
> Lines <- "a    b    c    d
>     +    -    +   +
>     +    +    +   -   
>     +    1    -   '+ '
>     -    +    +   +
>     +    N    -   +"
> 
> 
> DF <- read.table(textConnection(Lines), header = TRUE)
> cnames <- colnames(DF)
> nrow <-length(rownames(DF))
> 
> nc <- length(cnames)
> NDF <- data.frame(matrix(c(rep(0,nc*nrow)),ncol=nc))
> 
> for (i in 1:length(cnames)) {
>   NDF[,i] <- sapply(DF[,i],function(x) if (x=="+") {1} else {if (x=="-")
> {0} else {-1}} )
> }
> colnames(NDF) <- cnames
> 
> But this is shure one loop too much. Please give me the R way solution.

library(car)

DF[] <- lapply(DF, function(x){recode(x, "'+'=1; '-'=0; else=-1")})

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-- 
Chuck Cleland, Ph.D.
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