[R] data frame manipulation with condition

[Uwe Ligges]

On 24.02.2012 16:59, Arnaud Gaboury wrote:
> TY Uwe,
>
> So I will have to write a line for each condition? Right?
>
> In fact I was trying to do something with apply in one line, but couldn't achieve any result. In fact, all my transformation will be multiplying one object by a specific number according to the value of df$x.

In that case:

mult <- c(AA = 10, BB = 25)

Then:


df$y <- df$y * mult[df$x]


Uwe Ligges


>
> Arnaud Gaboury
>
> A2CT2 Ltd.
>
>
> -----Original Message-----
> From: Uwe Ligges [mailto:ligges at statistik.tu-dortmund.de]
> Sent: vendredi 24 février 2012 16:33
> To: Arnaud Gaboury
> Cc: r-help at r-project.org
> Subject: Re: [R] data frame manipulation with condition
>
>
>
> On 24.02.2012 16:25, Arnaud Gaboury wrote:
>> Dear list,
>>
>> n00b question, but still can't find any easy answer.
>>
>> Here is a df:
>
>
> Change
>
>>> df<-data.frame(cbind(x=c("AA","BB","CC","AA"),y=1:4))
>
> to
>
>    df<- data.frame(x = c("AA","BB","CC","AA"), y = 1:4)
>
> to make your object a sensible data.frame.
>
>
>
>>> 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$y*10
>
> df$y[df$x=="AA"]<- df$y[df$x=="AA"] * 25
>
> ...
>
>
> Uwe Ligges
>
>
>>    if df$x=="BB" then df$y=df$y*25
>
>
>
>
>> and so on with other conditions.
>>
>> TY for any help.
>>
>> Trading
>>
>> A2CT2 Ltd.
>>
>>
>> Arnaud Gaboury
>>
>> A2CT2 Ltd.
>>
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>> and provide commented, minimal, self-contained, reproducible code.
>