Converting code to R Question
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 library(psych) # score (scores <- score.multiple.choice(key, dat, total=TRUE, short=FALSE)) dat$Variable <- scores$scores Best, Ista
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.
Craig
**********
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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