Generate all Combinations of xCm in R Programming – combn() Function

combn() function in R Language is used to generate all combinations of the elements of x taken m at a time.

Syntax: combn(x, m)

Parameters:
x: total number of elements taken
r: number of elements taken at a time out of “x” elements

Example 1:

# R program to illustrate
# combn function

# Calling the combn() function
combn(5, 3)
combn(6, 5)
combn(2, 2)

Output:

     [, 1] [, 2] [, 3] [, 4] [, 5] [, 6] [, 7] [, 8] [, 9] [, 10]
[1, ]    1    1    1    1    1    1    2    2    2     3
[2, ]    2    2    2    3    3    4    3    3    4     4
[3, ]    3    4    5    4    5    5    4    5    5     5

     [, 1] [, 2] [, 3] [, 4] [, 5] [, 6]
[1, ]    1    1    1    1    1    2
[2, ]    2    2    2    2    3    3
[3, ]    3    3    3    4    4    4
[4, ]    4    4    5    5    5    5
[5, ]    5    6    6    6    6    6

     [, 1]
[1, ]    1
[2, ]    2

Example 2:

# R program to illustrate
# combn function

# Calling the combn() function
combn(LETTERS[1: 4], 2)
combn(LETTERS[2: 6], 3)

Output:

     [, 1] [, 2] [, 3] [, 4] [, 5] [, 6]
[1, ] "A"  "A"  "A"  "B"  "B"  "C" 
[2, ] "B"  "C"  "D"  "C"  "D"  "D" 

     [, 1] [, 2] [, 3] [, 4] [, 5] [, 6] [, 7] [, 8] [, 9] [, 10]
[1, ] "B"  "B"  "B"  "B"  "B"  "B"  "C"  "C"  "C"  "D"  
[2, ] "C"  "C"  "C"  "D"  "D"  "E"  "D"  "D"  "E"  "E"  
[3, ] "D"  "E"  "F"  "E"  "F"  "F"  "E"  "F"  "F"  "F"