Generate All Combinations of n Elements in R | /cn/2007/04/generate-all-combinations-of-n-elements-in-r/

# Your vector  
vec <- c(letters[1:5])

# Create an empty list  
lst <- list()

# Define total number combinations from 1-pair to comb_n-pair  
comb_n <- length(vec)

# Find all possible combinations up to 5, store it to a list  
for (i in 1:comb_n) {  
lst[[i]]<- c(combn(vec, i, simplify = FALSE))  
}

# For all elements in the list, print pairs  
for (i in 1:comb_n) {  
# Find length of list number i  
k<-length(lst[[i]])

# For all elements in list i, print pairs  
for(j in 1:k){  
print(lst[[i]][[j]])  
}  
}