combinations {arrangements} | R Documentation |
This function generates all the combinations of selecting k
items from n
items.
The results are in lexicographical order.
combinations(x = NULL, k = NULL, n = NULL, v = NULL, freq = NULL, replace = FALSE, layout = NULL, nitem = -1L, skip = NULL, index = NULL, nsample = NULL, drop = NULL)
x |
an integer or a vector, will be treated as |
k |
an integer, the number of items drawn, defaults to |
n |
an integer, the total number of items, its value may be implicitly deduced from |
v |
a vector to be drawn, defaults to |
freq |
an integer vector of item repeat frequencies |
replace |
an logical to draw items with replacement |
layout |
if "row", "column" or "list" is specified, the returned value would be a "row-major" matrix, a "column-major" matrix or a list respectively |
nitem |
number of combinations required, usually used with |
skip |
the number of combinations skipped |
index |
a vector of indices of the desired combinations |
nsample |
sampling random combinations |
drop |
vectorize a matrix or unlist a list |
icombinations for iterating combinations and ncombinations to calculate number of combinations
# choose 2 from 4 combinations(4, 2) combinations(LETTERS[1:3], k = 2) # multiset with frequencies c(2, 3) combinations(k = 3, freq = c(2, 3)) # with replacement combinations(4, 2, replace = TRUE) # column major combinations(4, 2, layout = "column") # list output combinations(4, 2, layout = "list") # specifc range of combinations combinations(4, 2, nitem = 2, skip = 3) # specific combinations combinations(4, 2, index = c(3, 5)) # random combinations combinations(4, 2, nsample = 3) # zero sized combinations dim(combinations(5, 0)) dim(combinations(5, 6)) dim(combinations(0, 0)) dim(combinations(0, 1))