CODEWITHSUNDEEP
javascript
Jon Sud
Jon Sud

Reputation: 11661

How to calc table cell position to array?

I have a table. each cell defiend by x,y position. for example cell number one is start at 0,0 and so on...

I want to take this table and turn it into this array of [x,y,x,y,x,y....].

For example for this picture the expected result should be this arr:

const arr = [0,0,200,0,400,0,0,200,200,200,400,200,0,400,200,400,400,400];

enter image description here

The problem is I have only this data to work with:

const cols = 3;
const tableWidth = 600;
const colHeight = 200;
const items = 9;
const cellWidth = tableWidth / cols;

So I try to do a function that over all the items and try to figure out the x and the y. but I have no clue how to do that in one for only.

const arr = [];

for (var i = 0; i < items; i++) {

  const even = i % 2 === 0;

  const x = ???;
  const y = i * colHeight;

  table.push(x,y);
}

console.log({ arr });

Upvotes: 1

Views: 95

Answers (1)

Kirill Simonov
Kirill Simonov

Reputation: 8491

I suggest you to calculate the number of rows and then iterate over rows and columns using 2 for loops - it will be more readable:

const cols = 3;
const tableWidth = 600;
const colHeight = 200;
const items = 9;

const cellWidth = tableWidth / cols;
const rows = items / cols;

const arr = [];

for (let i = 0; i < rows; i++) {
  for (let j = 0; j < cols; j++) {
    const x = j * cellWidth;
    const y = i * colHeight;
    arr.push(x, y);
  }
}

console.log(arr);

UPDATE: if you still want one for loop, try the following approach:

const cols = 3;
const tableWidth = 600;
const colHeight = 200;
const items = 9;

const cellWidth = tableWidth / cols;

const arr = [];

for (let i = 0; i < items; i++) {
  const col = i % cols;
  const row = Math.floor(i * cols / items);
  arr.push(col * cellWidth, row * colHeight);
}

console.log(arr);

Upvotes: 2

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