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Joshua Wiley

2010-Jan-14 07:05 UTC

[R] Better way than an ifelse statement?

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/

Ista Zahn

2010-Jan-14 07:22 UTC

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[R] Better way than an ifelse statement?

There is a recode function in the Hmisc package that might help:

library(Hmisc)
example$X3 <- recode(example$X2, 1:4, c(-3,-1,1,3))

-Ista

On Thu, Jan 14, 2010 at 2:05 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/
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Ista Zahn
Graduate student
University of Rochester
Department of Clinical and Social Psychology
http://yourpsyche.org

Petr PIKAL

2010-Jan-14 07:31 UTC

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[R] Odp: Better way than an ifelse statement?

Hi

r-help-bounces at r-project.org napsal dne 14.01.2010 08:05:14:
> 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
One way is with factor

as.numeric(as.character(factor(example$X2, labels=c(-3, -1,1,3))))

Regards
Petr

> 
> 
> Thanks for your help,
> 
> Joshua
> 
> -- 
> Joshua Wiley
> Senior in Psychology
> University of California, Riverside
> http://www.joshuawiley.com/
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
http://www.R-project.org/posting-guide.html> and provide commented, minimal, self-contained, reproducible code.

Henrique Dallazuanna

2010-Jan-14 10:55 UTC

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[R] Better way than an ifelse statement?

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/
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O

Romain Francois

2010-Jan-14 11:03 UTC

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[R] Better way than an ifelse statement?

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
Professional R Enthusiast
+33(0) 6 28 91 30 30
http://romainfrancois.blog.free.fr
|- http://tr.im/KfKn : Rcpp 0.7.2
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Joshua Wiley

2010-Jan-14 13:39 UTC

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[R] Better way than an ifelse statement?

Hello,

Thanks for all of your responses.  I got a lot of great options that work.

Thanks again!


Joshua

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