Split 16x16 matrix in 4x4 in the same matrix-CodePudding

Hi guys I am doing a small exercise splitting a 16x16 matrix in 4x4 chunks, creating a sort of diagonal of small matrix. I am representing the 4x4 matrix with a value of 1 and the rest with a value of 0, painting them in the big matrix itself.

This what it should look like:

"1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0"
"1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0"
"1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0"
"1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0"
"0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1"
"0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1"
"0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1"
"0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1"
"1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0"
"1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0"
"1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0"
"1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0"
"0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1"
"0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1"
"0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1"
"0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1"

This is what I have achieved at me moment:

The red squares is what I am missing. These 4x4 matrix has to be "1" as well.

This is code (it is in javascript but I don't really care about the language).

let m = Array(16)
    .fill("0")
    .map(() => Array(16).fill("0"));

for (let i = 0; i < m.length; i  ) {
    for (let j = 0; j < m.length; j  ) {
        if (i % 8 < 4 && j % 8 < 4) {
            m[i][j] = "1";
        }
    }
}

m.map((a) => console.log(JSON.stringify(a   "")));

Anyone know how to solve this problem? Thank You in advance!

CodePudding user response：

I've try something like that: it uses even/odd comparison to determine position for "1"

let m = Array(16)
    .fill("")
    .map(() => Array(16).fill(""));

for (let i = 0; i < m.length; i  ) {
    for (let j = 0; j < m.length; j  ) {
        let mi = parseInt(i/4);
        let mj = parseInt(j/4);
        m[i][j] = ((mi&1) == (mj&1))?"1":"0";
    }
}

m.map((a) => console.log(JSON.stringify(a   "")));

CodePudding user response：

In Ruby:

require 'matrix'

m = Matrix.build(16, 16) { |i,j| (i/4).even? != (j/4).even? ? 0 : 1 }

To convert the matrix object to an array:

m.to_a
  #=> [[1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0],
  #    [1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0],
  #    [1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0],
  #    [1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0],
  #    [0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1],
  #    [0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1],
  #    [0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1],
  #    [0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1],
  #    [1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0],
  #    [1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0],
  #    [1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0],
  #    [1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0],
  #    [0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1],
  #    [0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1],
  #    [0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1],
  #    [0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1]]

See Matrix::build and Enumerable#to_a.

This should translate easily to other languages that have a matrix library, but even if such a library is not available, the clause

(i/4).even? != (j/4).even? ? 0 : 1

shows how the array can be constructed in an economic way.