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

Using your data frame d,

library(tidyr)
> spread(d, key = b, value = c)
    a aa bb cc
1   1 30 50 50
2   2 45 35 40
3   3 30 40 40
4   4 50 40 50
5   5 50 20 40
6   6 20 50 40
7   7 35 25 35
8   8 50 20 40
9   9 35 30 30
10 10 35 50 25

Explanation, the argument key = b lets you specify a column in your data frame. spread will create a new column for each unique entry in the key column b. The argument value = c tells spread to retrieve the value in column c and write it in the corresponding new key column.