Randomizing Grids

Grids are common in assessments, and nodes often need to be placed on the grid randomly.

The method RandomDraws.FromGridWithoutReplacement() simplifies the process of randomly placing nodes on a grid. This method takes n, rows, and columns arguments. It returns an array of n objects to represent the randomly chosen grid cells. The grid cells have row and column properties (these are 0-based). The grid cell positions are unique.

This code returns an array of 2 grid cells, each with a unique row and column, from a grid with 4 rows and 4 columns:

const cells = RandomDraws.FromGridWithoutReplacement(2, 4, 4);

The cells object might look like this

[
  { row: 2, column: 2 },
  { row: 0, column: 2 },
]

Below, we create a 6 x 6 grid. We randomly place an X on 4 grid cells. The cell positions are also printed to the console.

Click the "Run" button multiple times to see how the positions of the X change.

Run

Explore:

Advanced: RandomDraws.FromGridWithoutReplacement() optionally takes a fourth argument, predicate, which is a function that takes row and column arguments and returns a boolean indicating if the cell meets a certain condition. This is useful if we need to apply a restriction to the grid randomization. Perhaps certain cells are not allowed to be chosen, or chosen cells must follow a certain pattern. For example, if need to restrict chosen cells to the diagonal, we could add a predicate function:
```
const cells = RandomDraws.FromGridWithoutReplacement(4, 6, 6, (row, column) => {
    if (row === column) {
        return true;
    } else {
        return false;
    }
});
```