data frame manipulation with conditions

TY Elai for your answer. One solution has been given earlier in this list by Sarah Goslee and William Dunlap.

Arnaud Gaboury

A2CT2 Ltd.


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of ilai
Sent: vendredi 24 f?vrier 2012 20:14
To: A2CT2 Trading
Cc: r-help at r-project.org
Subject: Re: [R] data frame manipulation with conditions

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.