# Creating a Matrix From a Vector in R

I have a vector with two columns, one column containing numerical values and one column containing names.I'm a novice to R but essentially I want to take a vector and create a matrix with it wherein the values within the matrix would add together. So for example, where the vector A has a value of 1 and B has a value of 1, in the matrix at the intersection of A and B I want the values to add and become 2.

I've tried to use a for loop but I'm having trouble with the arguments to put within the loop. Any help would be greatly appreciated and I'd be glad to clarify stuff if it doesn't make sense.

Essentially what I want is to take this: A 1 B 0 C 0 D 1 And turn it into this:

A B C D A 1 1 2 B 1 0 1 C 1 0 1 D 2 1 1

Thanks!

## Answers

R > x <- c(1,0,0,1) R > outer(x, x, "+") [,1] [,2] [,3] [,4] [1,] 2 1 1 2 [2,] 1 0 0 1 [3,] 1 0 0 1 [4,] 2 1 1 2

The next thing is to ignore the diagonal. Updated by Vincent:

names(x) <- c("A","B","C","D")