extract list elements and concatenate into a string in r - r

Question

using the variable list below I want to for all combinations, join the variables into a string seperated by "+"
l_ALLVar_list <- c("a","b","c","d","z1","z2","z3")
I have the code to generate the 127 combinations
all_combos=do.call("c", lapply(seq_along(l_ALLVar_list), function(i) combn(l_ALLVar_list, i, FUN = list)))
and using position 66 as an example
> all_combos[66]
[[1]]
[1] "a" "b" "c" "z2"
I want to be able to join the elements of these at index 66 into the string a+b+c+z2
I have tried
str_c(c(lol[66]),collapse=',')
but it comes back as
c(\"weight\", \"length\", \"wheel_base\", \"city_mpg\")
paste(all_combos[66], collapse = '')
produces the same again
any help would be appreciated

Answer 1

You can use the FUN argument in combn to paste all the combinations of l_ALLVar_list in one call, eliminating the need for your all_combos list.
unlist(lapply(seq_along(l_ALLVar_list), combn, x=l_ALLVar_list, paste, collapse="+"))
# [1] "a" "b" "c" "d" "z1"
# [6] "z2" "z3" "a+b" "a+c" "a+d"
# [11] "a+z1" "a+z2" "a+z3" "b+c" "b+d"
# [16] "b+z1" "b+z2" "b+z3" "c+d" "c+z1"
# [21] "c+z2" "c+z3" "d+z1" "d+z2" "d+z3"
# [26] "z1+z2" "z1+z3" "z2+z3" "a+b+c" "a+b+d"
# [31] "a+b+z1" "a+b+z2" "a+b+z3" "a+c+d" "a+c+z1"
# [36] "a+c+z2" "a+c+z3" "a+d+z1" "a+d+z2" "a+d+z3"
# [41] "a+z1+z2" "a+z1+z3" "a+z2+z3" "b+c+d" "b+c+z1"
# [46] "b+c+z2" "b+c+z3" "b+d+z1" "b+d+z2" "b+d+z3"
# [51] "b+z1+z2" "b+z1+z3" "b+z2+z3" "c+d+z1" "c+d+z2"
# [56] "c+d+z3" "c+z1+z2" "c+z1+z3" "c+z2+z3" "d+z1+z2"
# [61] "d+z1+z3" "d+z2+z3" "z1+z2+z3" "a+b+c+d" "a+b+c+z1"
# [66] "a+b+c+z2" "a+b+c+z3" "a+b+d+z1" "a+b+d+z2" "a+b+d+z3"
# [71] "a+b+z1+z2" "a+b+z1+z3" "a+b+z2+z3" "a+c+d+z1" "a+c+d+z2"
# [76] "a+c+d+z3" "a+c+z1+z2" "a+c+z1+z3" "a+c+z2+z3" "a+d+z1+z2"
# [81] "a+d+z1+z3" "a+d+z2+z3" "a+z1+z2+z3" "b+c+d+z1" "b+c+d+z2"
# [86] "b+c+d+z3" "b+c+z1+z2" "b+c+z1+z3" "b+c+z2+z3" "b+d+z1+z2"
# [91] "b+d+z1+z3" "b+d+z2+z3" "b+z1+z2+z3" "c+d+z1+z2" "c+d+z1+z3"
# [96] "c+d+z2+z3" "c+z1+z2+z3" "d+z1+z2+z3" "a+b+c+d+z1" "a+b+c+d+z2"
#[101] "a+b+c+d+z3" "a+b+c+z1+z2" "a+b+c+z1+z3" "a+b+c+z2+z3" "a+b+d+z1+z2"
#[106] "a+b+d+z1+z3" "a+b+d+z2+z3" "a+b+z1+z2+z3" "a+c+d+z1+z2" "a+c+d+z1+z3"
#[111] "a+c+d+z2+z3" "a+c+z1+z2+z3" "a+d+z1+z2+z3" "b+c+d+z1+z2" "b+c+d+z1+z3"
#[116] "b+c+d+z2+z3" "b+c+z1+z2+z3" "b+d+z1+z2+z3" "c+d+z1+z2+z3" "a+b+c+d+z1+z2"
#[121] "a+b+c+d+z1+z3" "a+b+c+d+z2+z3" "a+b+c+z1+z2+z3" "a+b+d+z1+z2+z3" "a+c+d+z1+z2+z3"
#[126] "b+c+d+z1+z2+z3" "a+b+c+d+z1+z2+z3"

Answer 2

Use lapply to do paste for each item in your list:
result <- unlist(lapply(all_combos,
function(c) do.call(paste, c(as.list(c), sep="+"))))
> result[66:70]
[1] "a+b+c+z2" "a+b+c+z3" "a+b+d+z1" "a+b+d+z2" "a+b+d+z3"