[R] How to add a variable to a dataframe whose values are conditional upon the values of an existing variable

[Greg Snow]

Here is another approach (I think this is the simplest):

daylkp <- c(SAT=1, SUN=2, MON=3, TUE=4, WED=5, THU=6, FRI=7)

tmp.in <- sample( names(daylkp), 25, TRUE )
tmp.out <- daylkp[tmp.in]

names(tmp.out) <- NULL # optional


hope this helps,

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Steve Matco
> Sent: Friday, February 26, 2010 12:32 PM
> To: r-help at r-project.org
> Subject: [R] How to add a variable to a dataframe whose values are
> conditional upon the values of an existing variable
> 
> Hi everyone,
> 
> I am at my wits end with what I believe would be considered simple by a
> more experienced R user. I want to know how to add a variable to a
> dataframe whose values are conditional on the values of an
> existing variable. I can't seem to make an ifelse statement work for my
> situation. The existing variable in my dataframe is a character
> variable named DOW which contains abbreviated day names (SAT, SUN,
> MON.....FRI). I want to add a numerical variable named DOW1 to my
> dataframe that will take on the value 1 if DOW equals "SAT", 2 if DOW
> equals "SUN", 3 if DOW equals "MON",.....,7 if DOW equals "FRI".
> I  know this must be a simple problem but I have searched everywhere
> and tried everything I could think of. Any help would be greatly
> appreciated.
> 
> Thank you,
> 
> Mike
> 
> 
> 
> 
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