array-of-arrays-sort-by-col npm package

API — `sortByCol()`

The main function sortByCol() is imported like this:

It is a function which takes two input arguments:

Input argument	Type	Obligatory	Description
	`arr` Type: Array of zero or more arrays Obligatory: yes
`arr`	Array of zero or more arrays	yes	Source of data to put into an AST

	`index` Type: Natural number or zero, like a number or string Obligatory: no
`index`	Natural number or zero, like a number or string	no	Which column to match the subarrays (rows) by? The default is `0` or the first element of each sub-array.

The function returns a sorted array.

You can import version:

Sorts array of arrays by any column (the default is the first element, zero’th column index).

The algorithm is tailored for integer-only values.

Consider this arrangement:

1 ----- 9 ----- 0
1 ---------------
1 ----- 8 ----- 2
1 ----- 7 ----- 5

In JS code, that’s:

[[1, 9, 0], [1], [1, 8, 2], [1, 7, 5]];

Default sorting is against first column (zero’th index), so result would be:

1 ----- 7 ----- 5
1 ----- 8 ----- 2
1 ----- 9 ----- 0
1 ---------------

Output in JS code:

[[1, 7, 5], [1, 8, 2], [1, 9, 0], [1]];

Rules:

When two rows are compared, the program compares by a particular column first (default is the first, zero-index column). Then, if values are equal, it looks around and compares by those values. First, compare left-side, then right-side. Then, if values are equal even there, we “ripple” outwards. First, compare left-side, then right-side. Then, if values are equal even there, we “ripple” outwards. …
Arrays normalised into a matrix, with absent values filled in as null, are accepted too. Same behaviour.

1 ---- 7 ------ 5
1 ---- 8 ------ 2
1 ---- 9 ------ 0
1 --- null -- null