How do you map every combination of categorical variables in R?

Question

Using R, is there a way to take a data set and map out every possible combination of every categorical variable?

For example, let\'s say I had 10,000 rows of custom

Answer 1

Here's a method that utilizes dplyr

require(magrittr)
require(dplyr)    

set.seed(123)
dat = data.frame(email=sample(c("yahoo", "gmail"), 10000, replace=T),
                 browser=sample(c("mozilla", "ie"), 10000, replace=T),
                 country=sample(c("usa", "canada"), 10000, replace=T),
                 money=runif(10000))  
dat %>%
  group_by(email, browser, country) %>%
  summarize(mean = mean(money))
# email browser country      mean
# 1 gmail      ie  canada 0.5172424
# 2 gmail      ie     usa 0.4921908
# 3 gmail mozilla  canada 0.4934892
# 4 gmail mozilla     usa 0.4993923
# 5 yahoo      ie  canada 0.5013214
# 6 yahoo      ie     usa 0.5098280
# 7 yahoo mozilla  canada 0.4985357
# 8 yahoo mozilla     usa 0.4919743

EDIT: if you want to pass a list into group_by(), you'll need to use the not-non-standard evaluation counterpart, regroup(). For example,

mylist <- list("email", "browser", "country")
dat %>%
  regroup(mylist) %>%
  summarize(mean = mean(money))

also see dplyr: How to use group_by inside a function?