Reshape in R without aggregation (for example MTurk response strings)

Question

Ordinarily, I\'d use a pretty basic long-to-wide reshape for this, but it seems to be dropping my aggregation variables. The setup is I had a job on mechanical Turk that I perfo

Answer 1

If your data is in a data.table it's a one-liner can be done as follows:

library(data.table)    
mturk.dt <- as.data.table(mturk)

mturk.dt[, as.list(
         rbind(c(Answer.Q1thing, AssignmentStatus))
         )
        , by=list(Id=Input.id, State=Input.State)]

Note that the by argument handles the name-changing too!

---

If you want to properly name the other columns, use setnames after the fact or, more dynamically, using setattr within the j=.. argument as follows:

After the Fact:

## Assuming 'res' is the reshaped data.table form above:
## Change the names of the six V1, V2.. columns 
setnames(res, paste0("V", 1:6), c(paste0("Answer", 1:3), paste0("Status", 1:3)))

Dynamically, in j=..

## Use `as.data.table` instead of `as.list`, to preserve new names
mturk.dt[, as.data.table(
         rbind(c(
              setattr(Answer.Q1thing,   "names", paste0("Answer", seq(Answer.Q1thing  )))
            , setattr(AssignmentStatus, "names", paste0("Status", seq(AssignmentStatus)))
            ))
         )
        , by=list(Id=Input.id, State=Input.State)]

       Id State Answer1 Answer2  Answer3  Status1  Status2  Status3
1: 134231    NY Myguess Myguess BadGuess Approved Approved Approved
2: 134812    CA Myguess Myguess BadGuess Approved Approved Approved