[R] Converting code to R Question
istazahn at gmail.com
Tue Feb 26 03:11:44 CET 2013
If you do this sort of thing a lot you may find the psych package helpful:
# make example data
x <- 1:3
dat <- data.frame(expand.grid(Item1=x, Item2=x, Item3=x, Item4=x))
# make scoring ky
key <- c(Item1=1, Item2=2, Item3=1, Item4=1)
# load psych library
(scores <- score.multiple.choice(key, dat, total=TRUE, short=FALSE))
dat$Variable <- scores$scores
On Mon, Feb 25, 2013 at 8:02 PM, Craig J <cjohns38 at gmail.com> wrote:
> I'm learning R and am converting some code from SPSS into R. My background
> is in SAS/SPSS so the vectorization is new to me and I'm trying to learn
> how to NOT use loops...or use them sparingly. I'm wondering what the
> most efficient to tackle a problem I'm working on is. Below is an example
> piece of code. Essentially what it does is set a variable to zero, loop
> through item responses, and add one if a condition is met. For example, if
> item one was responded as a 1 then add one to the final variable. If item
> two was responded as a 2 then add one to the final variable. I have to do
> this for five scales with each scale having 6 items half of which may have
> the 1 response pattern and half the 2 pattern.
> Any suggestions on how best to tackle this in R would be helpful.
> Old SPSS code sample
> Compute Variable = 0.
> IF (item1 = 1) Variable = Variable +1 .
> IF (item2= 2) Variable = Variable +1 .
> IF (item3 = 1) Variable = Variable +1.
> IF (item4 = 2) Variable = Variable +1.
> EXECUTE .
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> and provide commented, minimal, self-contained, reproducible code.
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