[R] Create variable with AND IF statement

[David Winsemius]

On Jan 2, 2012, at 4:11 AM, Richard Kolodziej wrote:

> Hello,
>
> I'm using SPSS at work but really would like to switch to R. Right  
> now I'm
> trying to learn R in reproducing calculations I did with SPSS but am  
> stuck
> with something that is quite simple and comprehensible in SPSS-Syntax:
>
> IF (variable1.fac = 0 AND variable2.num = 0) variable3=1.
> IF (variable1.fac = 0 AND variable2.num >= 1) variable3=2.
> IF (variable1.fac = 1 AND variable2.num = 0) variable3=3.
> IF (variable1.fac = 1 AND variable2.num >= 1) variable3=4.


>
> I want to create four different groups out of different conditions  
> of two
> variables:
>  * variable1.fac is a factor coded with 0 and 1
>  * variable2.num is a numerical variable with only whole numbers
>
> My problem with R is that I can't find a way to use AND in an IF  
> statement
> that doesn't produce an error or not intended solutions.
>
> "An Introduction to R" is really unhelpful with this problem and I  
> wouldn't
> have written here, if I didn't have searched for the answer.
>

Do you not find the 'ifelse' function described in "An Introduction to  
R" in the section regarding "if".



> http://tolstoy.newcastle.edu.au/R/help/05/09/12136.html was helpful in
> understanding how the IF statement is written in R but didn't answer  
> my
> question how to add an usable AND (&, |)

Not the best answer I have ever seen in the archives. But if you had  
followed up by reading further in the thread you would have found the  
correct approach.

> https://stat.ethz.ch/pipermail/r-help/2008-November/178808.html looked
> promising but didn't do what I had intended

(I think the results of interaction( variable1.fac = 0 , variable2.num  
= 0) should have dome very nicely, but if you wanted them a naked  
numbers then this would have also givne satisfaction:

var3 <- as.numeric( interaction( variable1.fac = 0 , variable2.num =  
0) )

-- 
David
>
> Thanks in advance,
> Richard
>
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>
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David Winsemius, MD
West Hartford, CT