Respacer

Respacer is a library for adjusting the position of points or line-segments to avoid overlaps.

It accepts an array of objects, each of which has a property storing its 1D position, and returns a new array containing the objects with an added property storing the adjusted position. The array is sorted by this position.

It is similar to labella.js, but differs both in method used (it solves a Quadratic Program rather than doing a force based simulation), and in API (it accepts an array of arbitrary objects, rather than an array of labella.Node objects).

Usage

For points

The repositionPoints(data, options) function is used to reposition objects which do not have individual widths.

The optional argument options is an object in which the following properties can be set:

Name	Type	Default	Description
width	number	1000	The maximum position value that can be assigned. Note that if this is too small, the problem may not be satisfiable.
minSpacing	number	10	The minimum distance between adjacent points after repositioning.
oldPositionName	string	x	The name of the property which contains the original position.
newPositionName	string	newX	The name of the property in which the updated position will be stored.

For example, the input array

const data = [
    {x: 4, label: "A"},
    {x: 9, label: "B"},
    {x: 2, label: "C"},
    {x: 13, label: "D"},
    {x: 9, label: "E"},
    {x: 9.1, label: "F"}
];

const newPositions = repositionPoints(data);

returns:

[
    {
        "x": 2,
        "label": "C",
        "newX": 0
    },
    {
        "x": 4,
        "label": "A",
        "newX": 10.000000000000005
    },
    {
        "x": 9,
        "label": "B",
        "newX": 20
    },
    {
        "x": 9,
        "label": "E",
        "newX": 30
    },
    {
        "x": 9.1,
        "label": "F",
        "newX": 39.999999999999986
    },
    {
        "x": 13,
        "label": "D",
        "newX": 49.999999999999986
    }
]

For line segments

The repositionLineSegments(data, options) function is used to reposition objects which do have individual widths.

The optional argument options is an object in which the following properties can be set:

Name	Type	Default	Description
width	number	1000	The maximum position value that can be assigned. Note that if this is too small, the problem may not be satisfiable.
minSpacing	number	10	The minimum distance between adjacent the end of one object (position + width) and the start of the next after repositioning.
oldPositionName	string	x	The name of the property which contains the original position of each object.
widthName	string	width	The name of the property which contains the width of each object.
newPositionName	string	newX	The name of the property in which the updated position will be stored.

For example,

const data = [
    {x: 4, width: 3},
    {x: 5, width: 4},
    {x: 2, width: 5},
    {x: 9, width: 6},
    {x: 5, width: 7}
];


const repositionedData = repositionLineSegments(data);

returns:

[
    {
        "x": 2,
        "width": 5,
        "newX": 0
    },
    {
        "x": 4,
        "width": 3,
        "newX": 4.999999999999999
    },
    {
        "x": 5,
        "width": 4,
        "newX": 7.999999999999998
    },
    {
        "x": 5,
        "width": 7,
        "newX": 12
    },
    {
        "x": 9,
        "width": 6,
        "newX": 18.999999999999996
    }
]

Importing

Using script tag

You can make respacer available in the global scope using a <script> tag:

<script src="../dist/bundle.js"></script>

You can then use the respacer.repositionPoints() and respacer.repositionLineSegments() methods from within JavaScript on that page.

The files in examples/ provides complete working examples.

You can generate this bundle file from the source code in this repository by running npm install and then npm build.

Alternatively, you can use a copy of the file served by various CDNs, including:

• https://cdn.jsdelivr.net/npm/respacer/dist/bundle.js
• https://unpkg.com/respacer/dist/bundle.js

As a commonjs module

You can use respacer as a CommonJS module:

const {repositionPoints, repositionLineSegments} = require('./reposition');

const data = [
    {x: 4, label: "A"},
    {x: 9, label: "B"},
    {x: 2, label: "C"},
    {x: 13, label: "D"},
    {x: 9, label: "E"},
    {x: 9.1, label: "F"}
];

const repositionedData = repositionPoints(data);