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, because I don't want to auto-number columns, just widen multiple columns. It's also kind of like this question, but again, I don't think I want the columns to vary with a row value as in that answer. Or, a valid answer to this question is to convince me it's exactly like one of the others. The solution in the second question of "two dcasts plus a merge" is the most attractive right now, because it is comprehensible to me.
foo:
foo = data.frame(group=c('a', 'a', 'b', 'b', 'c', 'c'),
times=c('before', 'after', 'before', 'after', 'before', 'after'),
action_rate=c(0.1,0.15, 0.2, 0.18,0.3, 0.35),
num_users=c(100, 100, 200, 200, 300, 300))
foo <- transform(foo,
action_rate_c95 = 1.95 * sqrt(action_rate*(1-action_rate)/num_users))
> foo
group times action_rate num_users action_rate_c95
1 a before 0.10 100 0.05850000
2 a after 0.15 100 0.06962893
3 b before 0.20 200 0.05515433
4 b after 0.18 200 0.05297400
5 c before 0.30 300 0.05159215
6 c after 0.35 300 0.05369881
foo2:
foo2 <- data.frame(group=c('a', 'b', 'c'),
action_rate_before=c(0.1,0.2, 0.3),
action_rate_after=c(0.15, 0.18,0.35),
action_rate_c95_before=c(0.0585,0.055, 0.05159),
action_rate_c95_after=c(0.069, 0.0530,0.0537),
num_users=c(100, 200, 300))
> foo2
group action_rate_before action_rate_after action_rate_c95_before
1 a 0.1 0.15 0.0585
2 b 0.2 0.18 0.0550
3 c 0.3 0.35 0.05159
action_rate_c95_after num_users
1 0.0690 100
2 0.0530 200
3 0.0537 300
EDIT: Now I'd probably try to do it with pivot_wider from tidyr.
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