Convert data frame common rows to columns

Question

Say I have a data frame where one column is some repeating value (dates, IDs, etc). Is there a way to convert a data frame into a now data frame with columns instead of rep

Answer 1

With split and cbind:

> ll = lapply(split(d, d$b), function(x) x[3])
> dd = do.call(cbind, ll)
> names(dd) = names(ll)
> dd
   aa bb cc
1  30 50 50
2  45 35 40
3  30 40 40
4  50 40 50
5  50 20 40
6  20 50 40
7  35 25 35
8  50 20 40
9  35 30 30
10 35 50 25