[R] list contingency tables

[David Winsemius]

Seems like you are trying to recreate the calculations needed to perform 
an exact test. Why not look at the code for that or even easier, just 
use the function.

-- 

David.

On 11/8/18 8:05 PM, li li wrote:
> Hi all,
>    I am trying to list all the 4 by 2 tables with some fixed margins.
>    For example, consider 4 by 2 tables with row margins 1,2,2,1 and
> column margins 3,3. I was able to do it using the code below. However,
> as seen below, I had to first count the total number of tables with
> the specific row margins and column margins in order to create space
> to store the tables.
> Is there a way to skip the step of counting the number of tables?
>    Also, wanted to avoid for loops as much as possible since it can be
> extremely slow and inefficient.
>     Thanks so much in advance for you insight and help.
>         Hanna
>
>
>
>> library(gtools)
>> A <- permutations(n=4,r=2,v=0:3, repeats.allowed=TRUE)
>> B <- apply(A, 1, sum)
>> rmg <- c(1,2,2,1)
>> cmg <- c(3,3)
>> m1 <- t(A[which(B==1),])
>> m2 <- t(A[which(B==2),])
>> m3 <- t(A[which(B==2),])
>>
>> ##count number of tables with row margins 1,2,2,1 and column margins 3,3.
>> num <- 0
>> for (i in 1:ncol(m1)){
> +     for (j in 1:ncol(m2)){
> +         for (k in 1:ncol(m3)){
> +             M <- t(cbind(m1[,i], m2[,j], m3[,k]))
> +             M1 <- rbind(M, cmg-apply(M,2,sum))
> +             num <- num+(sum(M1[4,] < 0) == 0)
> +         }}}
>>
>> #create space to store the tables
>> C <- array(NA, dim=c(4,2,num))
>>
>> # list all the tables with fixed margins
>> num <- 0
>> for (i in 1:ncol(m1)){
> +     for (j in 1:ncol(m2)){
> +         for (k in 1:ncol(m3)){
> +             M <- t(cbind(m1[,i], m2[,j], m3[,k]))
> +             M1 <- rbind(M,cmg-apply(M,2,sum))
> +             if (sum(M1[4,] < 0) == 0) {
> +                 num <- num+1
> +                C[,,num] <- M1
> +             }
> +         }}}
>> C
> , , 1
>
>       [,1] [,2]
> [1,]    0    1
> [2,]    0    2
> [3,]    2    0
> [4,]    1    0
>
> , , 2
>
>       [,1] [,2]
> [1,]    0    1
> [2,]    1    1
> [3,]    1    1
> [4,]    1    0
>
> , , 3
>
>       [,1] [,2]
> [1,]    0    1
> [2,]    1    1
> [3,]    2    0
> [4,]    0    1
>
> , , 4
>
>       [,1] [,2]
> [1,]    0    1
> [2,]    2    0
> [3,]    0    2
> [4,]    1    0
>
> , , 5
>
>       [,1] [,2]
> [1,]    0    1
> [2,]    2    0
> [3,]    1    1
> [4,]    0    1
>
> , , 6
>
>       [,1] [,2]
> [1,]    1    0
> [2,]    0    2
> [3,]    1    1
> [4,]    1    0
>
> , , 7
>
>       [,1] [,2]
> [1,]    1    0
> [2,]    0    2
> [3,]    2    0
> [4,]    0    1
>
> , , 8
>
>       [,1] [,2]
> [1,]    1    0
> [2,]    1    1
> [3,]    0    2
> [4,]    1    0
>
> , , 9
>
>       [,1] [,2]
> [1,]    1    0
> [2,]    1    1
> [3,]    1    1
> [4,]    0    1
>
> , , 10
>
>       [,1] [,2]
> [1,]    1    0
> [2,]    2    0
> [3,]    0    2
> [4,]    0    1
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.