R help - Aug 2011 - If find x, then y, else do nothing

I want to write code that says "If you find an element equal to 4 in this
vector for each person in the data set tested separately, then put in 1 for
2 and 2 for 4, else leave the variable as is"

 u.ppl <- (unique(init.dat1$grid))
      l.ppl <- length(u.ppl)
        for (i in 1:l.ppl)
        {
          if (grep("4",init.dat1$Slide1_RESP)) {2 == 1, 4 == 2}; else
init.dat1$Slide1_RESP

        }

-- 
Edward H. Patzelt
Research Assistant – TRiCAM Lab
University of Minnesota – Psychology/Psychiatry
VA Medical Center
Office: S355 Elliot Hall - Twin Cities Campus
Phone: 612-626-0072  Email: patze003@umn.edu

Please consider the environment before printing this email
www.psych.umn.edu/research/tricam

	[[alternative HTML version deleted]]

Hi Edward,

You can try something like:

u.ppl <- unique(init.dat1$grid)
l.ppl <- ifelse(grepl(4, init.dat1$Slide1_RESP), 2,
                init.dat1$Slide1_RESP)

Note that this is not exact as you have not provided a reproducible
example.  I am not exactly sure how you are  putting 1 for 2 and 2 for
4, if the value is equal to 4, but presumably it is clearer with data.
 In any event, look at ?ifelse it is something like a vectorized if
statement and is, I believe, preferable to your use of a for loop.  I
can probably give you a runnable solution if you can give the first
few rows of the relevant data.

Cheers,

Josh

On Fri, Aug 5, 2011 at 2:15 PM, Edward Patzelt <patze003 at umn.edu>
wrote:
> I want to write code that says "If you find an element equal to 4 in
this
> vector for each person in the data set tested separately, then put in 1 for
> 2 and 2 for 4, else leave the variable as is"
>
> ?u.ppl <- (unique(init.dat1$grid))
> ? ? ?l.ppl <- length(u.ppl)
> ? ? ? ?for (i in 1:l.ppl)
> ? ? ? ?{
> ? ? ? ? ?if (grep("4",init.dat1$Slide1_RESP)) {2 == 1, 4 == 2};
else
> init.dat1$Slide1_RESP
>
> ? ? ? ?}
>
> --
> Edward H. Patzelt
> Research Assistant ? TRiCAM Lab
> University of Minnesota ? Psychology/Psychiatry
> VA Medical Center
> Office: S355 Elliot Hall - Twin Cities Campus
> Phone: 612-626-0072 ?Email: patze003 at umn.edu
>
> Please consider the environment before printing this email
> www.psych.umn.edu/research/tricam
>
> ? ? ? ?[[alternative HTML version deleted]]
>
>
> ______________________________________________
> 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.
>
>


-- 
Joshua Wiley
Ph.D. Student, Health Psychology
Programmer Analyst II, ATS Statistical Consulting Group
University of California, Los Angeles
https://joshuawiley.com/