How to assemble a matrix in R being the values the subtraction of values of a vector

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How to create an array in R, whose values are the result of a subtraction of values from a vector? ex.:

Vector

x <- c(a, b, c)

Matrix

1 a-a  a-b  a-c
2 b-a  b-b  b-c
3 c-a  b-b  c-c
r matrix

2 answers

4


The function outer was made to answer the question problem. By default it assumes the function "*" to calculate the external product (Wikipedia Português, in English), but any other function may be passed.

a <- 1
b <- 3
c <- 6
x <- c(a, b, c)

outer(x, x, '-')
#     [,1] [,2] [,3]
#[1,]    0   -2   -5
#[2,]    2    0   -3
#[3,]    5    3    0

1

Just think of the matrix as a set of vectors, then you form the rows and columns and join in a matrix.
Here already done at once, I create a vector with the concatenated lines and then transform into a matrix with 3 lines.

x <- c(1,2,3)

m <- matrix(c(x[1]-x, x[2]-x, x[3] - x), nrow =  3, byrow = T)

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