R help - Feb 2012 - data frame manipulation with conditions

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))
> df
   x y
1 AA 1
2 BB 2
3 CC 3
4 AA 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.

TY for any help.

Trading
?
A2CT2 Ltd.

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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