rmatrixcombinationselement

Combination of N elements with q elements in R


I have N=6 elements and q=3 elements symboled as 0,1,2.

I want to create all the vectors of N=6 elements with 2 elements equal to 0, 2 elements equal to 1 and 2 elements equal to 2 in all the possible positions.

The number of these vectors are equal to combn(6,2)*combn(4,2)*combn(2,2)=90.

Here is a code that construct these 90 vectors in the matrix F:

N=6
x<-c(1:N)
#########################################
A<-combn(x,2)
B<-matrix(0,ncol(A),length(x)) 
for( i in 1:ncol(A) ) 
{ 
y<-rep(0,N) 
y[A[1:nrow(A),i]]<-1 
B[i,]<-y 
}
######################################
E<-matrix(0,nrow(B),length(x)-nrow(A))  
for( i in 1:nrow(B) ) 
{ 
q=0 
for( j in 1:ncol(B) ) 
{ 
if( B[i,j]!=1 )  
{ 
q=q+1 
E[i,q]<-j 
}}}
########################################
ASD<-combn(E[i,],2) 
F<-matrix(0,nrow(B)*ncol(ASD),length(x)) 
q=0 
for( i in 1:nrow(B) ) 
{ 
ASD<-combn(E[i,],2) 
for( j in 1:ncol(ASD) ) 
{ 
B[i,ASD[1:nrow(ASD),j]]<-2 
q=q+1 
F[q,]<-B[i,] 
B[i,ASD[1:nrow(ASD),j]]<-0 
}}

Is there any other less complicated way to do it?


Solution

  • You can use the iterpc package:

    > library(iterpc)
    > I <- iterpc(c(2,2,2), labels=c(0,1,2), ordered=TRUE)
    > getall(I)
          [,1] [,2] [,3] [,4] [,5] [,6]
     [1,]    0    0    1    1    2    2
     [2,]    0    0    1    2    1    2
     [3,]    0    0    1    2    2    1
     [4,]    0    0    2    1    1    2
     [5,]    0    0    2    1    2    1
     [6,]    0    0    2    2    1    1
     [7,]    0    1    0    1    2    2
     [8,]    0    1    0    2    1    2
     [9,]    0    1    0    2    2    1
    [10,]    0    1    1    0    2    2
    [11,]    0    1    1    2    0    2
    [12,]    0    1    1    2    2    0
    [13,]    0    1    2    0    1    2
    [14,]    0    1    2    0    2    1
    [15,]    0    1    2    1    0    2
    [16,]    0    1    2    1    2    0
    [17,]    0    1    2    2    0    1
    [18,]    0    1    2    2    1    0
    [19,]    0    2    0    1    1    2
    [20,]    0    2    0    1    2    1
    [21,]    0    2    0    2    1    1
    [22,]    0    2    1    0    1    2
    [23,]    0    2    1    0    2    1
    [24,]    0    2    1    1    0    2
    [25,]    0    2    1    1    2    0
    [26,]    0    2    1    2    0    1
    [27,]    0    2    1    2    1    0
    [28,]    0    2    2    0    1    1
    [29,]    0    2    2    1    0    1
    [30,]    0    2    2    1    1    0
    [31,]    1    0    0    1    2    2
    [32,]    1    0    0    2    1    2
    [33,]    1    0    0    2    2    1
    [34,]    1    0    1    0    2    2
    [35,]    1    0    1    2    0    2
    [36,]    1    0    1    2    2    0
    [37,]    1    0    2    0    1    2
    [38,]    1    0    2    0    2    1
    [39,]    1    0    2    1    0    2
    [40,]    1    0    2    1    2    0
    [41,]    1    0    2    2    0    1
    [42,]    1    0    2    2    1    0
    [43,]    1    1    0    0    2    2
    [44,]    1    1    0    2    0    2
    [45,]    1    1    0    2    2    0
    [46,]    1    1    2    0    0    2
    [47,]    1    1    2    0    2    0
    [48,]    1    1    2    2    0    0
    [49,]    1    2    0    0    1    2
    [50,]    1    2    0    0    2    1
    [51,]    1    2    0    1    0    2
    [52,]    1    2    0    1    2    0
    [53,]    1    2    0    2    0    1
    [54,]    1    2    0    2    1    0
    [55,]    1    2    1    0    0    2
    [56,]    1    2    1    0    2    0
    [57,]    1    2    1    2    0    0
    [58,]    1    2    2    0    0    1
    [59,]    1    2    2    0    1    0
    [60,]    1    2    2    1    0    0
    [61,]    2    0    0    1    1    2
    [62,]    2    0    0    1    2    1
    [63,]    2    0    0    2    1    1
    [64,]    2    0    1    0    1    2
    [65,]    2    0    1    0    2    1
    [66,]    2    0    1    1    0    2
    [67,]    2    0    1    1    2    0
    [68,]    2    0    1    2    0    1
    [69,]    2    0    1    2    1    0
    [70,]    2    0    2    0    1    1
    [71,]    2    0    2    1    0    1
    [72,]    2    0    2    1    1    0
    [73,]    2    1    0    0    1    2
    [74,]    2    1    0    0    2    1
    [75,]    2    1    0    1    0    2
    [76,]    2    1    0    1    2    0
    [77,]    2    1    0    2    0    1
    [78,]    2    1    0    2    1    0
    [79,]    2    1    1    0    0    2
    [80,]    2    1    1    0    2    0
    [81,]    2    1    1    2    0    0
    [82,]    2    1    2    0    0    1
    [83,]    2    1    2    0    1    0
    [84,]    2    1    2    1    0    0
    [85,]    2    2    0    0    1    1
    [86,]    2    2    0    1    0    1
    [87,]    2    2    0    1    1    0
    [88,]    2    2    1    0    0    1
    [89,]    2    2    1    0    1    0
    [90,]    2    2    1    1    0    0
    

    EDIT 2018-04-28

    iterpc is now deprecated in favor of arrangements.