Day 22 Challenge is to extract the specific column from a matrix (list of array).

For example, a matrix with `[[1, 1, 1, 2], [0, 5, 0, 4], [2, 1, 3, 6]]`

which is has 3 index with 4 values/columns on each array.

If I draw it will be like this

```
[
[1, 1, 1, 2],
[0, 5, 0, 4],
[2, 1, 3, 6]
]
```

Since this is list of array, if I want to extract ONLY the SECOND column (in this case the THIRD value because an array index always start at `0`

index) that will give me an output `[1, 0, 3]`

, I will use `.map`

.

The way it works is, by looping the `matrix`

using `.map`

, it will return each array that I called it as `element`

, and return the value of each `column`

from the array using `element[column]`

.

This is the JavaScript solution

```
function extractMatrixColumn(matrix, column) {
return matrix.map(element => element[column]);
}
```

The test case

```
const matrix = [[1, 1, 1, 2], [0, 5, 0, 4], [2, 1, 3, 6]];
const column = 2;
extractMatrixColumn(matrix, column); // [1, 0, 3]
```

## Top comments (2)

Good one mate, you combine

`.map`

with destructuring assignment 👍