[R] data frame manipulation with conditions
ilai
keren at math.montana.edu
Fri Feb 24 20:14:11 CET 2012
On Fri, Feb 24, 2012 at 8:11 AM, A2CT2 Trading <trading at a2ct2.com> wrote:
> Dear list,
>
> n00b question, but still can't find any easy answer.
>
> Here is a df:
>
>> df<-data.frame(cbind(x=c("AA","BB","CC","AA"),y=1:4))
# No, your y is a factor
str(df)
'data.frame': 4 obs. of 2 variables:
$ x: Factor w/ 3 levels "AA","BB","CC": 1 2 3 1
$ y: Factor w/ 4 levels "1","2","3","4": 1 2 3 4
# You want to remove the cbind
> df<-data.frame(x=c("AA","BB","CC","AA"),y=1:4)
> str(df)
'data.frame': 4 obs. of 2 variables:
$ x: Factor w/ 3 levels "AA","BB","CC": 1 2 3 1
$ y: int 1 2 3 4
> I want to modify this df this way :
> if df$x=="AA" then df$y=df$y*10
> if df$x=="BB" then df$y=df$y*25
>
> and so on with other conditions.
>
df$y<- df$y * c(10,25,.5)[df$x]
[1] 10.0 50.0 1.5 40.0
# 1*10 2*25 3*.5 4*10
HTH
Elai
> TY for any help.
>
> Trading
>
> A2CT2 Ltd.
>
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