generate all 2^(dim(S)) combinations of elements from a set S

RStudio_rawdatalistr_untitled_C4A976C6

# `expand(df, nesting(patient, PCP), event_type)`
#   generates all unique combinations in `(patient, PCP) x event_type`.
#   That is; there will be `n_distinct(df$event_type)` rows per `patient, PCP`
#   tuple in the data
#  
#  df <- tibble(x = 1:4, y = letters[1:4]) 
# testthat::expect_equivalent(expand(df, nesting(x, y)), distinct(df, x, y)) 
# testthat::expect_equivalent(expand(df, crossing(x, y)), expand(df, x, y))

# generate all combinations of elements in a set S

dim_S <- 6
S <- letters[1:dim_S]
S_ <- rlang::rep_named(S, list(0:1)) %>% as_tibble()
expand_S <- lift_dl(partial(expand, data = S_))
combs <- expand_S(map(names(S_), sym))
combs <- combs %>% 
  pmap(.f = c) %>% 
  map(keep, .p = ~ ..1 == 1) %>% 
  map(names)