From long to wide data with multiple columns

Question

Suggestions for how to smoothly get from foo to foo2 (preferably with tidyr or reshape2 packages)?

This is kind of like this question, but not exactly I think, becau

Answer 1

You can use data.table instead of reshape2, because its dcast() function accepts several variables, and is faster too:

require(data.table)
setDT(foo)
dcast(foo,group+num_users~times,value.var=c("action_rate","action_rate_c95"))

   group num_users action_rate_after action_rate_before action_rate_c95_after action_rate_c95_before
1:     a       100              0.15                0.1            0.06962893             0.05850000
2:     b       200              0.18                0.2            0.05297400             0.05515433
3:     c       300              0.35                0.3            0.05369881             0.05159215

Answer 2

Here is a base R option with reshape

reshape(foo, idvar=c("group", "num_users"), timevar="times", direction="wide")
#  group num_users action_rate.before action_rate_c95.before action_rate.after
#1     a       100                0.1             0.05850000              0.15
#3     b       200                0.2             0.05515433              0.18
#5     c       300                0.3             0.05159215              0.35
#  action_rate_c95.after
#1            0.06962893
#3            0.05297400
#5            0.05369881

Answer 3

Here's another alternative using tidyr:

library(tidyr)
foo %>%
  gather(key, value, -group, -times, -num_users) %>%
  unite(col, key, times) %>%
  spread(col, value)

Which gives:

#  group num_users action_rate_after action_rate_before action_rate_c95_after
#1     a       100              0.15                0.1            0.06962893
#2     b       200              0.18                0.2            0.05297400
#3     c       300              0.35                0.3            0.05369881
#  action_rate_c95_before
#1             0.05850000
#2             0.05515433
#3             0.05159215