How to Generate All Possible Combinations of Vectors Without Caring for Order

How to generate all possible combinations of vectors without caring for order?

There's the combn function in the utils package:

t(combn(LETTERS[1:3],2))
#      [,1] [,2]
# [1,] "A"  "B" 
# [2,] "A"  "C" 
# [3,] "B"  "C"

I'm a little confused as to why your x has duplicated values.

Generate all possible n choose 2 pairs from a vector in R, efficient and fast

As pointed out by @Arun, you can use combn

> t(combn(x, 2))
     [,1] [,2]
[1,]    1    2
[2,]    1    3
[3,]    1    4
[4,]    2    3
[5,]    2    4
[6,]    3    4

How to get list of all combinations of pairs of character strings in R

An option is combn

combn(v1, 2, simplify = FALSE)

data

v1 <- paste0("pred_", 1:3)

How to list all permutations of events which happened in the right order?

I came to a similar conclusion using lapply

df <- lapply(1:nrow(events), function(x) {
              expand.grid(events$name[x], events$name[(x+1):nrow(events)])})
do.call(rbind, df[-nrow(events)])
#>    Var1    Var2
#> 1   sow   water
#> 2   sow harvest
#> 3 water harvest

R: generate all permutations of vector without duplicated elements

Using gtools package:

require(gtools)
permutations(n = 9, r = 3, v = 1:9)
# n -> size of source vector
# r -> size of target vector
# v -> source vector, defaults to 1:n
# repeats.allowed = FALSE (default)

R get all common elements for all possible combinations of N variables

Lots of ways, here's one:

grid <- expand.grid(a=c(T,F), b=c(T,F), c=c(T,F))
grid$results <- mapply(function(x,y,z) {
    unique(c(if(x) a,if(y) b,if(z) c))
},grid$a,grid$b,grid$c)

Output:

      a     b     c                results
1  TRUE  TRUE  TRUE x1, x2, x3, x4, x5, x6
2 FALSE  TRUE  TRUE     x2, x5, x3, x4, x6
3  TRUE FALSE  TRUE     x1, x2, x3, x4, x6
4 FALSE FALSE  TRUE             x3, x4, x6
5  TRUE  TRUE FALSE     x1, x2, x3, x4, x5
6 FALSE  TRUE FALSE                 x2, x5
7  TRUE FALSE FALSE         x1, x2, x3, x4
8 FALSE FALSE FALSE                   NULL

Generate all possible combinations of rows in R?

You can combine all the data as below:

do.call(cbind.data.frame,Map(expand.grid,teacher=teachers,students=students))

   name.teacher name.students height.teacher height.students smart.teacher smart.students
1           Ben          John            130             111           yes             no
2         Craig          John            101             111           yes             no
3         Mindy          John            105             111           yes             no
4           Ben          Mary            130              93           yes             no
5         Craig          Mary            101              93           yes             no
6         Mindy          Mary            105              93           yes             no
:            :            :                :               :            :              :
:            :            :                :               :            :              :

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