R help - Feb 2008 - Combining series of variables using identifier

R users,

I have df like this

a <- data.frame(    indx =    1:20,
                    var1 =    rep(c("I20", "I40",
"A50", "B60"), each=5),
                    var1_lab= rep(c("cat", "dog",
"mouse", "horse"), each=5),
                    var2 =    rep(c("B20", "X40",
"D50", "G60"), each=5),
                    var2_lab= rep(c("car", "bicycle",
"train", "bus"), each=5))
str(a)

I'd like to create new variables by combining "varX" and
"varX_lab" like this:

a$var1_new <- factor(paste(a$var1, a$var1_lab, sep=": "))
a$var2_new <- factor(paste(a$var2, a$var2_lab, sep=": "))
a

But, in the real world, I have multiple df:s and many of variables
named by the same manner. Is there a possibility to create a function
which combines these variables and creates new ones into the same df
using "varX" as an identifier?

Many thanks,
Lauri

Hi,

if the columns always follow the same order (indx,var#, var#_lab ...), 
then You could use the column numbers and do the following:

1) CN<-colnames(df)[#] (#=colnum of 'var#')
2) df$NEW<-(here the expression to create the new variable)
3) colnames(df)[ncol(df)]<-c(paste(CN,"new",sep="_"))

This can easily be built in a loop.

Hope this helps,
Kimmo

Lauri Nikkinen kirjoitti viestiss??n (26.02.2008):
> R users,
>
> I have df like this
>
> a <- data.frame(    indx =    1:20,
>                     var1 =    rep(c("I20", "I40",
"A50", "B60"),
> each=5), var1_lab= rep(c("cat", "dog",
"mouse", "horse"), each=5),
> var2 =    rep(c("B20", "X40", "D50",
"G60"), each=5), var2_lab> rep(c("car",
"bicycle", "train", "bus"), each=5)) str(a)
>
> I'd like to create new variables by combining "varX" and
"varX_lab"
> like this:
>
> a$var1_new <- factor(paste(a$var1, a$var1_lab, sep=": "))
> a$var2_new <- factor(paste(a$var2, a$var2_lab, sep=": "))
> a
>
> But, in the real world, I have multiple df:s and many of variables
> named by the same manner. Is there a possibility to create a function
> which combines these variables and creates new ones into the same df
> using "varX" as an identifier?
>
> Many thanks,
> Lauri
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html and provide commented,
> minimal, self-contained, reproducible code.

Try this:

foo <- function(data, ...)
{
patt <- grep("var[0-9]$", names(data), value=T)
res <- paste(sapply(data[, patt], as.character), sapply(data[,
paste(patt, "lab", sep="_")], as.character), sep=":
")
cbind(a, matrix(res, ncol=length(patt), dimnames=list(NULL,
paste(patt, "new", sep="_"))))
}

foo(a)

On 26/02/2008, Lauri Nikkinen <lauri.nikkinen at iki.fi>
wrote:
> R users,
>
>  I have df like this
>
>  a <- data.frame(    indx =    1:20,
>                     var1 =    rep(c("I20", "I40",
"A50", "B60"), each=5),
>                     var1_lab= rep(c("cat", "dog",
"mouse", "horse"), each=5),
>                     var2 =    rep(c("B20", "X40",
"D50", "G60"), each=5),
>                     var2_lab= rep(c("car", "bicycle",
"train", "bus"), each=5))
>  str(a)
>
>  I'd like to create new variables by combining "varX" and
"varX_lab" like this:
>
>  a$var1_new <- factor(paste(a$var1, a$var1_lab, sep=": "))
>  a$var2_new <- factor(paste(a$var2, a$var2_lab, sep=": "))
>  a
>
>  But, in the real world, I have multiple df:s and many of variables
>  named by the same manner. Is there a possibility to create a function
>  which combines these variables and creates new ones into the same df
>  using "varX" as an identifier?
>
>  Many thanks,
>  Lauri
>
>  ______________________________________________
>  R-help at r-project.org mailing list
>  https://stat.ethz.ch/mailman/listinfo/r-help
>  PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
>  and provide commented, minimal, self-contained, reproducible code.
>

-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O