Expanding a list of numbers into a matrix (list with n values to multiply to a n x n matrix)-CodePudding

I have a set of numbers, which I want to expand into a matrix. There are 4 values in the list which I want to expand into a 4x4 matrix. Here is some example data

freq <- c(627,449,813,111)

I want to expand this into a matrix of so that it's like this. Apologies I have just copied and pasted data, thus it's not an R output, but hope it helps to get the idea across.

    1   2   3   4   Total
1   197 141 255 35  627
2   141 101 183 25  449
3   255 183 330 45  813
4   35  25  45  6   111
    627 449 813 111 2000

The cells are multiplication of the (row total)x(column total)/(table total). The value in 1,1 = (627 x 627)/2000 = 197. The value in 2,1 = (627 x 449)/2000 = 141, and so on.

Is there a function that will create this matrix? I will try to do it via a loop but was hoping there is a function or matrix calculation trick that can do this more efficiently? Apologies if I didn't articulate the above too well, any help is greatly appreciated. Thanks

CodePudding user response：

freq <- c(627,449,813,111) 
round(outer(freq, freq)/sum(freq))
#>      [,1] [,2] [,3] [,4]
#> [1,]  197  141  255   35
#> [2,]  141  101  183   25
#> [3,]  255  183  330   45
#> [4,]   35   25   45    6