CODEWITHSUNDEEP
rpattern-matchingcharactercombinationspermutation
Sarath Chandra
Sarath Chandra

Reputation: 31

Combination search for character vector

a<-c('a','b','c','d')

Need this to be segregated in combinations

Required output is 

(a b c d,a b c,b c d,a b,b c,c d,a,b,c,d)

Upvotes: 2

Views: 171

Answers (2)

Joseph Wood
Joseph Wood

Reputation: 7597

The desired output can be built from the power set of c('a', 'b', 'c', 'd') = letters[1:4]. Using the powerset function from the rje library, we have:

unlist(lapply(rje::powerSet(letters[1:4])[-1], paste0, collapse = ' '))
[1] "a"       "b"       "a b"     "c"       "a c"     "b c"     "a b c"  
[8] "d"       "a d"     "b d"     "a b d"   "c d"     "a c d"   "b c d"  
[15] "a b c d"

Upvotes: 0

drJones
drJones

Reputation: 1233

I used @chinsoon12 suggestions with a further paste to get your required output:

paste(lapply(unlist(lapply(rev(seq_along(a)), function(m) combn(a, m, simplify=FALSE)), recursive=FALSE), paste, collapse=" "), collapse=",")

Returns: "a b c d,a b c,a b d,a c d,b c d,a b,a c,a d,b c,b d,c d,a,b,c,d"

Upvotes: 1

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