I have a vector of integers from 0-9 and need all unique possible combinations of these consecutive vector elements, including the original elements.
> vec <- 0:9
> vec
[1] 0 1 2 3 4 5 6 7 8 9
The task is similar to this question. The major (and tricky) difference is that I only need consecutive combinations (e.g "0", "01", "012", ... "0123456789", ... "1", ... "123456789") and not non-consecutive combinations (such as "013").
How would I go about creating this subset of combinations?
Here is a nested sapply approach
unlist(
sapply(
seq_along(vec),
function(k) {
sapply(
k:length(vec),
function(l) paste0(vec[k:l], collapse = "")
)
}
)
)
which produces
[1] "0" "01" "012" "0123" "01234"
[6] "012345" "0123456" "01234567" "012345678" "0123456789"
[11] "1" "12" "123" "1234" "12345"
[16] "123456" "1234567" "12345678" "123456789" "2"
[21] "23" "234" "2345" "23456" "234567"
[26] "2345678" "23456789" "3" "34" "345"
[31] "3456" "34567" "345678" "3456789" "4"
[36] "45" "456" "4567" "45678" "456789"
[41] "5" "56" "567" "5678" "56789"
[46] "6" "67" "678" "6789" "7"
[51] "78" "789" "8" "89" "9"
Another option is sapply + embed
unlist(
sapply(
seq_along(vec),
function(k) {
do.call(paste0, rev(data.frame(embed(vec, k))))
}
)
)
which gives
[1] "0" "1" "2" "3" "4"
[6] "5" "6" "7" "8" "9"
[11] "01" "12" "23" "34" "45"
[16] "56" "67" "78" "89" "012"
[21] "123" "234" "345" "456" "567"
[26] "678" "789" "0123" "1234" "2345"
[31] "3456" "4567" "5678" "6789" "01234"
[36] "12345" "23456" "34567" "45678" "56789"
[41] "012345" "123456" "234567" "345678" "456789"
[46] "0123456" "1234567" "2345678" "3456789" "01234567"
[51] "12345678" "23456789" "012345678" "123456789" "0123456789"
Here is a one-liner with RcppAlgos (I am the author):
RcppAlgos::comboGeneral(10, 2, repetition = TRUE, FUN = function(r) {
paste((0:9)[r[1]:r[2]], collapse = "")
}, FUN.VALUE = "a")
[1] "0" "01" "012" "0123" "01234" "012345"
[7] "0123456" "01234567" "012345678" "0123456789" "1" "12"
[13] "123" "1234" "12345" "123456" "1234567" "12345678"
[19] "123456789" "2" "23" "234" "2345" "23456"
[25] "234567" "2345678" "23456789" "3" "34" "345"
[31] "3456" "34567" "345678" "3456789" "4" "45"
[37] "456" "4567" "45678" "456789" "5" "56"
[43] "567" "5678" "56789" "6" "67" "678"
[49] "6789" "7" "78" "789" "8" "89"
[55] "9"
Another possible solution, based on purrr::map:
library(tidyverse)
map(0:9, \(x) map(x:9, \(y) str_c(x:y, collapse = ""))) %>% unlist
#> [1] "0" "01" "012" "0123" "01234"
#> [6] "012345" "0123456" "01234567" "012345678" "0123456789"
#> [11] "1" "12" "123" "1234" "12345"
#> [16] "123456" "1234567" "12345678" "123456789" "2"
#> [21] "23" "234" "2345" "23456" "234567"
#> [26] "2345678" "23456789" "3" "34" "345"
#> [31] "3456" "34567" "345678" "3456789" "4"
#> [36] "45" "456" "4567" "45678" "456789"
#> [41] "5" "56" "567" "5678" "56789"
#> [46] "6" "67" "678" "6789" "7"
#> [51] "78" "789" "8" "89" "9"