[R] reduce three columns to one with the colnames

[Bert Gunter]

... and I could not resist adding (assuming the vectors are all  in a
data frame or matrix, yourdat):

apply(yourdat,1,function(x)c("blue","green","red")[as.logical(x)])

Cheers,
Bert



On Mon, May 13, 2013 at 8:39 AM, Gabor Grothendieck
<ggrothendieck at gmail.com> wrote:
> On Mon, May 13, 2013 at 10:24 AM, David Studer <studerov at gmail.com> wrote:
>> Hello everybody,
>>
>> I have three variables "blue", "green" and "red" containing values 0 (no)
>> and 1 (yes).
>>
>> How can I easily create another variable "colors" with the values "blue",
>> "green" and "red"?
>>
>
> Suppose
>
> blue <- c(1, 0, 0, 1)
> green <- c(0, 0, 1, 0)
> red <- c(0, 1, 0, 0)
>
> Here are a few possibilities:
>
> # 1
> factor(blue + 2 * green + 3 * red, labels = c("blue", "green", "red"))
>
> # 2
> paste0(
>    ifelse(blue, "blue", ""),
>    ifelse(green, "green", ""),
>    ifelse(red, "red", "")
> )
>
> # 3
> newvar <- character(length(blue))
> newvar[!!blue] <- "blue"
> newvar[!!green] <- "green"
> newvar[!!red] <- "red"
> newvar
>
> # 4
> c("blue", "green", "red")[blue + 2 * red + 3 * green]
>
> # 5
> library(car)
> recode(blue + 2 * green + 3 * red, "1='blue'; 2='green'; 3='red'")
>
>
> --
> Statistics & Software Consulting
> GKX Group, GKX Associates Inc.
> tel: 1-877-GKX-GROUP
> email: ggrothendieck at gmail.com
>
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-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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