[R] Better way than an ifelse statement?

[Romain Francois]

Or this ;

example$X3 <- c(-3, -1, 1, 3)[ example$X2 ]

Romain

On 01/14/2010 11:55 AM, Henrique Dallazuanna wrote:
>
> Try this:
>
> example$X3<-  sapply(example$X2, switch, -3, -1, 1, 3)
>
> On Thu, Jan 14, 2010 at 5:05 AM, Joshua Wiley<jwiley.psych at gmail.com>  wrote:
>> Hello All,
>>
>> I am trying to create a column of weights based off of factor levels
>> from another column.  I am using the weights to calculate L scores.
>> Here is an example where the first column are scores, the second is my
>> "factor" and the third I want to be a column of weights.  I can do
>> what I want with an ifelse statement (see below), but I am wondering
>> if anyone knows of a cleaner way to do this?
>>
>> example<- data.frame(cbind(rnorm(4), rep(1:4, 1), c(0)))
>>
>> example$X3<- ifelse(example$X2==1, -3, (
>> ifelse(example$X2==2, -1, (
>> ifelse(example$X2==3, 1, (
>> ifelse(example$X2==4, 3, NA))))))) ## this seems sloppy to me
>>
>>> example
>>            X1 X2 X3
>> 1  1.75308880  1 -3
>> 2 -0.49273616  2 -1
>> 3 -0.12446648  3  1
>> 4 -0.06417217  4  3
>>
>>
>> Thanks for your help,
>>
>> Joshua
>>
>> --
>> Joshua Wiley
>> Senior in Psychology
>> University of California, Riverside
>> http://www.joshuawiley.com/

-- 
Romain Francois
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