# [R] Odp: Combining all possible values of variables into a new...

Petr PIKAL petr.pikal at precheza.cz
Mon Oct 20 16:39:00 CEST 2008

```Hi

maybe you can change combination of your columns to factor

new <-factor(paste(x,y,z, sep=""))

and then reorder this factor (see reorder) change it to numeric to get
index

index <- as.numeric(factor)

and then choose from set of 144 data

data[index]

or use your index directly if you need just numbers from 1 to the final to

Maybe you could also look to permutations function from gtools package

Regards
Petr

r-help-bounces at r-project.org napsal dne 20.10.2008 16:10:26:

>
> I'm trying to create a new column in my data.frame where subjects are
> categorized depending on values on four other columns. In any other case
I
> would just nest a few ifelse statements, however, in this case i have
> 4*6*2*3=144 combinations and i get weird 'context overflow' errors. So I

> wonder if there is a more efficient way of doing this.
>
> For illustrational purposes, let's say i have:
>
> x<-c(1,0,0,1,0,0,1,0,0,1)
> y<-c(1,3,2,3,2,1,2,3,2,3)
> z<-c(1,2,1,2,1,2,1,2,1,2)
> d<-as.data.frame(cbind(x,y,z))
>
> and i do:
>
> d\$myvar <- ifelse(d\$x == 0 & d\$y==1 & d\$z==1 , d\$myvar <- 1,
> ifelse(d\$x == 0 & d\$y==1 & d\$z==2 , d\$myvar <- 2,
> ifelse(d\$x == 0 & d\$y==2 & d\$z==1 , d\$myvar <- 3,
> ifelse(d\$x == 0 & d\$y==2 & d\$z==2 , d\$myvar <- 4,
> ifelse(d\$x == 0 & d\$y==3 & d\$z==1 , d\$myvar <- 5,
> ifelse(d\$x == 0 & d\$y==3 & d\$z==2 , d\$myvar <- 6,
> ifelse(d\$x == 1 & d\$y==1 & d\$z==1 , d\$myvar <- 7,
> ifelse(d\$x == 1 & d\$y==1 & d\$z==2 , d\$myvar <- 8,
> ifelse(d\$x == 1 & d\$y==2 & d\$z==1 , d\$myvar <- 9,
> ifelse(d\$x == 1 & d\$y==2 & d\$z==2 , d\$myvar <- 10,
> ifelse(d\$x == 1 & d\$y==3 & d\$z==1 , d\$myvar <- 11,
> ifelse(d\$x == 1 & d\$y==3 & d\$z==2 , d\$myvar <- 12, NA))))))))))))
>
> Suggestions?
>
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