array-of-arrays-sort-by-col

sort array of arrays by column, rippling the sorting outwards from that column

Install

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

// consume as CommonJS require():
const sortByCol = require("array-of-arrays-sort-by-col");
// or as ES Module:
import sortByCol from "array-of-arrays-sort-by-col";

Here's what you'll get:

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Table of Contents

• Install
• What it does
• Sorting by certain column
• API
• Purpose of this library
• Contributing
• Licence

What it does

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

The algorithm is tailored for integer-only values.

Consider this input:

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 we compare two rows, first we compare by particular column (default is first, zero-index column). Then, if values are equal, we look around and compare 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. ...
• We accept arrays, normalised into a matrix, with absent value fillings set to null. Same behaviour.

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

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Sorting by certain column

For example, let's sort this array by second element (column index = 1):

const sortByCol = require("array-of-arrays-sort-by-col");
const input = [[1, 9, 0], [1], [1, 8, 2], [1, 7, 5]];
const result = sortByCol(input, 1);
console.log(
  `${`\u001b[${33}m${`input`}\u001b[${39}m`} = ${JSON.stringify(
    input,
    null,
    0
  )}`
);
// => input = [[1, 7, 5], [1, 8, 2], [1, 9, 0], [1]],

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API

sortByCol (arr, [index])

API - Input

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API - Output

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Purpose of this library

It will be a cornerstone of generate-ifs. There we turn list of characters (for example, astral-ones, pieces of emoji) into JS code which checks, if particular index anywhere within any of given character sequences. All character variations (if "a" followed by "b" OR "b" preceded by "a") are gathered into a single matrix where "root" axis column is the index from which we start checking.

This library will sort according to that axis column.

Outside of this case, this library could be used to sort two-dimensional arrays of integers against certain column, with "rippling" comparison (as opposed to first match by certain column, but if they're equal, just iterate from zero-th to last, skipping "certain"-one).

Practically, in human terms, this library makes sure the values clump around the particular column and "float" to the top as much as possible.

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Contributing

• If you see an error, raise an issue.
• If you want a new feature but can't code it up yourself, also raise an issue. Let's discuss it.
• If you tried to use this package, but something didn't work out, also raise an issue. We'll try to help.
• If you want to contribute some code, fork the monorepo via BitBucket, then write code, then file a pull request via BitBucket. We'll merge it in and release.

In monorepo, npm libraries are located in packages/ folder. Inside, the source code is located either in src/ folder (normal npm library) or in the root, cli.js (if it's a command line application).

The npm script "dev", the "dev": "rollup -c --dev --silent" builds the development version retaining all console.logs with row numbers. It's handy to have js-row-num-cli installed globally so you can automatically update the row numbers on all console.logs.

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Licence

MIT License

Copyright (c) 2015-2019 Roy Revelt and other contributors