Question

I have data from a survey. It comes from a question that looks like this:

Did you do any of the following activities during your PhD

                             Yes, paid by my school. Yes, paid by me.  No. 

Attended an internationl conference?
Bought textbooks? 

The data is automatically saved in a spreadsheet in this way:

id conf.1 conf.2 conf.3 text.1 text.2 text.3

1    1                              1
2           1               1
3                   1       1
4                   1                    1
5               

This means participant 1 attended a conference paid by her university; particiapnt 2 attended the conference paid by him, and participant 3 didn’t go.

I want to merge conf.1, conf.2 and conf.3 and text.1, text.2 and text.3 in single variables

id new.conf new.text

1   1        2
2   2        1
3   3        1
4   3        3

where the number now respresents the categories of the survey question

Thanks for your help

Answer 1

You don’t state whether or not each set of questions can have multiple answers. If so, this approach may not work for you. If that’s the case, I suggest making your question more reproducible before moving forward. With that caveat out of the way, give this a whirl:

library(reshape2)
#recreate your data
dat <- data.frame(id = 1:5,
                  conf.1 = c(1,rep(NA,4)),
                  conf.2 = c(NA,1, rep(NA,3)),
                  conf.3 = c(NA,NA,1,1, NA),
                  text.1 = c(NA,1,1,NA,NA),
                  text.2 = c(1, rep(NA,4)),
                  text.3 = c(rep(NA,3),1, NA))

#melt into long format
dat.m <- melt(dat, id.vars = "id")
#Split on the "."
dat.m[, c("variable", "val")] <- with(dat.m, colsplit(variable, "\\.", c("variable", "val")))
#Subset out only the complete cases
dat.m <- dat.m[complete.cases(dat.m),]
#Cast back into wide format
dcast(id ~ variable, value.var = "val", data = dat.m)
#-----
  id conf text
1  1    1    2
2  2    2    1
3  3    3    1
4  4    3    3