Generate list of all possible combinations of elements of vector
tidyr has a couple of options similar to expand.grid().
tidyr::crossing() returns a tibble and does not convert strings to factors (though you could do expand.grid(..., stringsAsFactors = F)).
library(tidyr)
crossing(var1 = 0:1, var2 = 0:1, var3 = 0:1)
# A tibble: 8 x 3
var1 var2 var3
<int> <int> <int>
1 0 0 0
2 0 0 1
3 0 1 0
4 0 1 1
5 1 0 0
6 1 0 1
7 1 1 0
8 1 1 1
tidyr::expand() can give both combinations of only values that appear in the data, like this:
expand(mtcars, nesting(vs, cyl))
# A tibble: 5 x 2
vs cyl
<dbl> <dbl>
1 0 4
2 0 6
3 0 8
4 1 4
5 1 6
or all possible combinations of two variables, even if there isn't an observation with those specific values in the data in the data, like this:
expand(mtcars, vs, cyl)
# A tibble: 6 x 2
vs cyl
<dbl> <dbl>
1 0 4
2 0 6
3 0 8
4 1 4
5 1 6
6 1 8
(You can see that there were no observations in the original data where vs == 1 & cyl == 8)
tidyr::complete() can also be used similar to expand.grid(). This is an example from the docs:
df <- dplyr::tibble(
group = c(1:2, 1),
item_id = c(1:2, 2),
item_name = c("a", "b", "b"),
value1 = 1:3,
value2 = 4:6
)
df %>% complete(group, nesting(item_id, item_name))
# A tibble: 4 x 5
group item_id item_name value1 value2
<dbl> <dbl> <chr> <int> <int>
1 1 1 a 1 4
2 1 2 b 3 6
3 2 1 a NA NA
4 2 2 b 2 5
This gives all possible combinations of item_id and item_name for each group - it creates a line for group=2 item_id=1 and item_name=a.
I discuss here a generic approach to solve all similar type of questions like this one. First let's see how the solutions evolve with increasing number of N to find out the general patterns.
First, the solution for length 1 is
0
1
Now for length 2, the solution becomes (2nd column separated by |):
0 | 0 0, 0 1
1 | 1 0, 1 1
Comparing it with previous solution for length 1, it is obvious that to obtain this new solution we simply append 0 and 1 to each of the previous solution (1st column, 0 and 1).
Now for length 3, the solution is (3rd column):
0 | 0 0 | 0 0 0, 0 0 1
1 | 1 0 | 1 0 0, 1 0 1
| 0 1 | 0 1 0, 0 1 1
| 1 1 | 1 1 0, 1 1 1
Again, this new solution is obtained by appending 0 and 1 to each of the previous solution (2nd column for length 2).
This observation naturally leads to a recursive solution. Assume we have already obtained our solution for length N-1 solution(c(0,1), N-1), to obtain solution of N we simply append 0 and 1 to each item of the solution N-1 append_each_to_list(solution(c(0,1), N-1), c(0,1)). Notice here how a more complex problem (solving N) is naturally decomposed to a simpler problem (solving N-1).
Then we just need to translate this plain English to R code almost literally:
# assume you have got solution for a shorter length len-1 -> solution(v, len-1)
# the solution of length len will be the solution of shorter length appended with each element in v
solution <- function(v, len) {
if (len<=1) {
as.list(v)
} else {
append_each_to_list(solution(v, len-1), v)
}
}
# function to append each element in vector v to list L and return a list
append_each_to_list <- function(L, v) {
purrr::flatten(lapply(v,
function(n) lapply(L, function(l) c(l, n))
))
}
To call the function:
> solution(c(1,0), 3)
[[1]]
[1] 1 1 1
[[2]]
[1] 0 1 1
[[3]]
[1] 1 0 1
[[4]]
[1] 0 0 1
[[5]]
[1] 1 1 0
[[6]]
[1] 0 1 0
[[7]]
[1] 1 0 0
As an alternative to @Justin's approach, you can also use CJ from the "data.table" package. Here, I've also made use of replicate to create my list of 14 zeroes and ones.
library(data.table)
do.call(CJ, replicate(14, 0:1, FALSE))
# V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 V11 V12 V13 V14
# 1: 0 0 0 0 0 0 0 0 0 0 0 0 0 0
# 2: 0 0 0 0 0 0 0 0 0 0 0 0 0 1
# 3: 0 0 0 0 0 0 0 0 0 0 0 0 1 0
# 4: 0 0 0 0 0 0 0 0 0 0 0 0 1 1
# 5: 0 0 0 0 0 0 0 0 0 0 0 1 0 0
# ---
# 16380: 1 1 1 1 1 1 1 1 1 1 1 0 1 1
# 16381: 1 1 1 1 1 1 1 1 1 1 1 1 0 0
# 16382: 1 1 1 1 1 1 1 1 1 1 1 1 0 1
# 16383: 1 1 1 1 1 1 1 1 1 1 1 1 1 0
# 16384: 1 1 1 1 1 1 1 1 1 1 1 1 1 1
You're looking for expand.grid.
expand.grid(0:1, 0:1, 0:1)
Or, for the long case:
n <- 14
l <- rep(list(0:1), n)
expand.grid(l)