combination-allowed_All-possible-permutations_letter.R

replicate(5, paste(sample(LETTERS, 2, replace=TRUE), collapse=""))

## [1] "GR" "WB" "BA" "RB" "KD"

##Combinations 
rep(list(c('A', 'G', 'T', 'C')), 4)

## [[1]]
## [1] "A" "G" "T" "C"
## 
## [[2]]
## [1] "A" "G" "T" "C"
## 
## [[3]]
## [1] "A" "G" "T" "C"
## 
## [[4]]
## [1] "A" "G" "T" "C"

x <- expand.grid(rep(list(c('A', 'G', 'T', 'C')), 4))
do.call(paste0, x)

##   [1] "AAAA" "GAAA" "TAAA" "CAAA" "AGAA" "GGAA" "TGAA" "CGAA" "ATAA" "GTAA"
##  [11] "TTAA" "CTAA" "ACAA" "GCAA" "TCAA" "CCAA" "AAGA" "GAGA" "TAGA" "CAGA"
##  [21] "AGGA" "GGGA" "TGGA" "CGGA" "ATGA" "GTGA" "TTGA" "CTGA" "ACGA" "GCGA"
##  [31] "TCGA" "CCGA" "AATA" "GATA" "TATA" "CATA" "AGTA" "GGTA" "TGTA" "CGTA"
##  [41] "ATTA" "GTTA" "TTTA" "CTTA" "ACTA" "GCTA" "TCTA" "CCTA" "AACA" "GACA"
##  [51] "TACA" "CACA" "AGCA" "GGCA" "TGCA" "CGCA" "ATCA" "GTCA" "TTCA" "CTCA"
##  [61] "ACCA" "GCCA" "TCCA" "CCCA" "AAAG" "GAAG" "TAAG" "CAAG" "AGAG" "GGAG"
##  [71] "TGAG" "CGAG" "ATAG" "GTAG" "TTAG" "CTAG" "ACAG" "GCAG" "TCAG" "CCAG"
##  [81] "AAGG" "GAGG" "TAGG" "CAGG" "AGGG" "GGGG" "TGGG" "CGGG" "ATGG" "GTGG"
##  [91] "TTGG" "CTGG" "ACGG" "GCGG" "TCGG" "CCGG" "AATG" "GATG" "TATG" "CATG"
## [101] "AGTG" "GGTG" "TGTG" "CGTG" "ATTG" "GTTG" "TTTG" "CTTG" "ACTG" "GCTG"
## [111] "TCTG" "CCTG" "AACG" "GACG" "TACG" "CACG" "AGCG" "GGCG" "TGCG" "CGCG"
## [121] "ATCG" "GTCG" "TTCG" "CTCG" "ACCG" "GCCG" "TCCG" "CCCG" "AAAT" "GAAT"
## [131] "TAAT" "CAAT" "AGAT" "GGAT" "TGAT" "CGAT" "ATAT" "GTAT" "TTAT" "CTAT"
## [141] "ACAT" "GCAT" "TCAT" "CCAT" "AAGT" "GAGT" "TAGT" "CAGT" "AGGT" "GGGT"
## [151] "TGGT" "CGGT" "ATGT" "GTGT" "TTGT" "CTGT" "ACGT" "GCGT" "TCGT" "CCGT"
## [161] "AATT" "GATT" "TATT" "CATT" "AGTT" "GGTT" "TGTT" "CGTT" "ATTT" "GTTT"
## [171] "TTTT" "CTTT" "ACTT" "GCTT" "TCTT" "CCTT" "AACT" "GACT" "TACT" "CACT"
## [181] "AGCT" "GGCT" "TGCT" "CGCT" "ATCT" "GTCT" "TTCT" "CTCT" "ACCT" "GCCT"
## [191] "TCCT" "CCCT" "AAAC" "GAAC" "TAAC" "CAAC" "AGAC" "GGAC" "TGAC" "CGAC"
## [201] "ATAC" "GTAC" "TTAC" "CTAC" "ACAC" "GCAC" "TCAC" "CCAC" "AAGC" "GAGC"
## [211] "TAGC" "CAGC" "AGGC" "GGGC" "TGGC" "CGGC" "ATGC" "GTGC" "TTGC" "CTGC"
## [221] "ACGC" "GCGC" "TCGC" "CCGC" "AATC" "GATC" "TATC" "CATC" "AGTC" "GGTC"
## [231] "TGTC" "CGTC" "ATTC" "GTTC" "TTTC" "CTTC" "ACTC" "GCTC" "TCTC" "CCTC"
## [241] "AACC" "GACC" "TACC" "CACC" "AGCC" "GGCC" "TGCC" "CGCC" "ATCC" "GTCC"
## [251] "TTCC" "CTCC" "ACCC" "GCCC" "TCCC" "CCCC"

length(unique(do.call(paste0, x)))

## [1] 256

expand.grid(height = seq(60, 80, 20), weight = seq(100, 300, 150),
            sex = c("Male","Female"))

##   height weight    sex
## 1     60    100   Male
## 2     80    100   Male
## 3     60    250   Male
## 4     80    250   Male
## 5     60    100 Female
## 6     80    100 Female
## 7     60    250 Female
## 8     80    250 Female

###################
l <- c("A", "B", "C")
combn(l, 2, paste, collapse="")

## [1] "AB" "AC" "BC"

unlist(lapply(1:2, function(n) combn(l, n, paste, collapse="")))

## [1] "A"  "B"  "C"  "AB" "AC" "BC"

combn(letters[1:4], 2)

##      [,1] [,2] [,3] [,4] [,5] [,6]
## [1,] "a"  "a"  "a"  "b"  "b"  "c" 
## [2,] "b"  "c"  "d"  "c"  "d"  "d"

combn(letters[1:4], 2, paste, collapse="")

## [1] "ab" "ac" "ad" "bc" "bd" "cd"

#ref https://stackoverflow.com/questions/54763028/all-possible-permutations-of-a-few-letters-with-varying-lengths-of-combination-a