Graph documentation

Contents

Overview

Graph is a visualization to display graphs and networks consisting of nodes and edges. The visualization is easy to use and supports custom shapes, styles, colors, sizes, images, and more.

The graph visualization works smooth on any modern browser for up to a few hundred nodes and edges.

To get started with Graph, install or download the vis.js library.

Example

Here a basic graph example. Note that unlike the Timeline, the Graph does not need the vis.css file.

More examples can be found in the examples directory. 

<!doctype html>
<html>
<head>
  <title>Graph | Basic usage</title>

  <script type="text/javascript" src="../../dist/vis.js"></script>
</head>

<body>

<div id="mygraph"></div>

<script type="text/javascript">
  // create an array with nodes
  var nodes = [
    {id: 1, label: 'Node 1'},
    {id: 2, label: 'Node 2'},
    {id: 3, label: 'Node 3'},
    {id: 4, label: 'Node 4'},
    {id: 5, label: 'Node 5'}
  ];

  // create an array with edges
  var edges = [
    {from: 1, to: 2},
    {from: 1, to: 3},
    {from: 2, to: 4},
    {from: 2, to: 5}
  ];

  // create a graph
  var container = document.getElementById('mygraph');
  var data= {
    nodes: nodes,
    edges: edges,
  };
  var options = {
    width: '400px',
    height: '400px'
  };
  var graph = new vis.Graph(container, data, options);
</script>

</body>
</html>

Loading

Install or download the vis.js library. in a subfolder of your project. Include the library script in the head of your html code: 

<script type="text/javascript" src="vis/dist/vis.js"></script>
The constructor of the Graph is vis.Graph. 
var graph = new vis.Graph(container, data, options);
The constructor accepts three parameters:

Data Format

The data parameter of the Graph constructor is an object which can contain different types of data. The following properties are supported in the data object:

Nodes

Nodes typically have an id and label. A node must contain at least a property id. Nodes can have extra properties, used to define the shape and style of the nodes.

A JavaScript Array with nodes is constructed like: 

var nodes = [
  {
    id: 1,
    label: 'Node 1'
  },
  // ... more nodes
];

Nodes support the following properties:

Name Type Required Description
color String | Object no Color for the node.
color.background String no Background color for the node.
color.border String no Border color for the node.
color.highlight String | Object no Color of the node when selected.
color.highlight.background String no Background color of the node when selected.
color.highlight.border String no Border color of the node when selected.
group Number | String no A group number or name. The type can be number, string, or an other type. All nodes with the same group get the same color schema.
fontColor String no Font color for label in the node.
fontFace String no Font face for label in the node, for example "verdana" or "arial".
fontSize Number no Font size in pixels for label in the node.
id Number | String yes A unique id for this node. Nodes may not have duplicate id's. Id's do not need to be consecutive. An id is normally a number, but may be any type.
image string no Url of an image. Only applicable when the shape of the node is image.
radius number no Radius for the node. Applicable for all shapes except box, circle, ellipse and database. The value of radius will override a value in property value.
shape string no Define the shape for the node. Choose from ellipse (default), circle, box, database, image, label, dot, star, triangle, triangleDown, and square.

In case of image, a property with name image must be provided, containing image urls.

The shapes dot, star, triangle, triangleDown, and square, are scalable. The size is determined by the properties radius or value.

When a property label is provided, this label will be displayed inside the shape in case of shapes box, circle, ellipse, and database. For all other shapes, the label will be displayed right below the shape.
label string no Text label to be displayed in the node or under the image of the node. Multiple lines can be separated by a newline character \n .
title string no Title to be displayed when the user hovers over the node. The title can contain HTML code.
value number no A value for the node. The radius of the nodes will be scaled automatically from minimum to maximum value. Only applicable when the shape of the node is dot. If a radius is provided for the node too, it will override the radius calculated from the value.
x number no Horizontal position in pixels. The horizontal position of the node will be fixed. The vertical position y may remain undefined.
y number no Vertical position in pixels. The vertical position of the node will be fixed. The horizontal position x may remain undefined.

Edges

Edges are connections between nodes. An edge must at least contain properties from and to, both referring to the id of a node. Edges can have extra properties, used to define the type and style.

A JavaScript Array with edges is constructed as: 

var edges = [
  {
    from: 1,
    to: 3
  },
  // ... more edges
];

Edges support the following properties:

Name Type Required Description
color string no A HTML color for the edge.
dash Object no Object containing properties for dashed lines. Available properties: length, gap, altLength.
dash.altLength number no Length of the alternated dash in pixels on a dashed line. Specifying dash.altLength allows for creating a dashed line with a dash-dot style, for example when dash.length=10 and dash.altLength=5. See also the option dahs.length. Only applicable when the line style is dash-line.
dash.length number no Length of a dash in pixels on a dashed line. Only applicable when the line style is dash-line.
dash.gap number no Length of a gap in pixels on a dashed line. Only applicable when the line style is dash-line.
fontColor String no Font color for the text label of the edge. Only applicable when property label is defined.
fontFace String no Font face for the text label of the edge, for example "verdana" or "arial". Only applicable when property label is defined.
fontSize Number no Font size in pixels for the text label of the edge. Only applicable when property label is defined.
from Number | String yes The id of a node where the edge starts. The type must correspond with the type of the node id's. This is normally a number, but can be any type.
length number no The length of the edge in pixels.
style string no Define a line style for the edge. Choose from line (default), arrow, arrow-center, or dash-line.
label string no Text label to be displayed halfway the edge.
title string no Title to be displayed when the user hovers over the edge. The title can contain HTML code.
to Number | String yes The id of a node where the edge ends. The type must correspond with the type of the node id's. This is normally a number, but can be any type.
value number no A value for the edge. The width of the edges will be scaled automatically from minimum to maximum value. If a width is provided for the edge too, it will override the width calculated from the value.
width number no Width of the line in pixels. The width will override a specified value, if a value is specified too.

DOT language

Graph supports data in the DOT language. To provide data in the DOT language, the data object must contain a property dot with a String containing the data.

Example usage: 

// provide data in the DOT language
var data = {
  dot: 'digraph {1 -> 1 -> 2; 2 -> 3; 2 -- 4; 2 -> 1 }'
};

// create a graph
var graph = new vis.Graph(container, data);

Configuration Options

Options can be used to customize the graph. Options are defined as a JSON object. All options are optional. 

var options = {
  width:  '100%',
  height: '400px',
  edges: {
    color: 'red',
    width: 2
  }
};

The following options are available.

Name Type Default Description
edges.color String "#2B7CE9" The default color of a edge.
edges.dash Object Object Object containing default properties for dashed lines. Available properties: length, gap, altLength.
edges.dash.altLength number none Default length of the alternated dash in pixels on a dashed line. Specifying dash.altLength allows for creating a dashed line with a dash-dot style, for example when dash.length=10 and dash.altLength=5. See also the option dahs.length. Only applicable when the line style is dash-line.
edges.dash.length number 10 Default length of a dash in pixels on a dashed line. Only applicable when the line style is dash-line.
edges.dash.gap number 5 Default length of a gap in pixels on a dashed line. Only applicable when the line style is dash-line.
edges.length Number 100 The default length of a edge.
edges.style String "line" The default style of a edge. Choose from line (default), arrow, arrow-center, dash-line.
edges.width Number 1 The default width of a edge.
groups Object none It is possible to specify custom styles for groups. Each node assigned a group gets the specified style. See Groups for an overview of the available styles and an example.
height String "400px" The height of the graph in pixels or as a percentage.
nodes.color String | Object Object Default color of the nodes. When color is a string, the color is applied to both background as well as the border of the node.
nodes.color.background String "#97C2FC" Default background color of the nodes
nodes.color.border String "#2B7CE9" Default border color of the nodes
nodes.color.highlight String | Object Object Default color of the node when the node is selected. Applied to both border and background of the node.
nodes.color.highlight.background String "#D2E5FF" Default background color of the node when selected.
nodes.color.highlight.border String "#2B7CE9" Default border color of the node when selected.
nodes.fontColor String "black" Default font color for the text label in the nodes.
nodes.fontFace String "sans" Default font face for the text label in the nodes, for example "verdana" or "arial".
nodes.fontSize Number 14 Default font size in pixels for the text label in the nodes.
nodes.group String none Default group for the nodes.
nodes.image String none Default image url for the nodes. only applicable with shape image.
nodes.widthMin Number 16 The minimum width for a scaled image. Only applicable with shape image.
nodes.widthMax Number 64 The maximum width for a scaled image. Only applicable with shape image.
nodes.shape String "ellipse" The default shape for all nodes. Choose from ellipse (default), circle, box, database, image, label, dot, star, triangle, triangleDown, and square. This shape can be overridden by a group shape, or by a shape of an individual node.
nodes.radius Number 5 The default radius for a node. Only applicable with shape dot.
nodes.radiusMin Number 5 The minimum radius for a scaled node. Only applicable with shape dot.
nodes.radiusMax Number 20 The maximum radius for a scaled node. Only applicable with shape dot.
selectable Boolean true If true, nodes in the graph can be selected by clicking them. Long press can be used to select multiple nodes.
stabilize Boolean true If true, the graph is stabilized before displaying it. If false, the nodes move to a stabe position visibly in an animated way.
width String "400px" The width of the graph in pixels or as a percentage.

Groups

It is possible to specify custom styles for groups of nodes. Each node having assigned to this group gets the specified style. The options groups is an object containing one or multiple groups, identified by a unique string, the groupname.

A group can have the following styles: 

var options = {
  // ...

  groups: {
    mygroup: {
      shape: 'circle',
      color: {
        border: 'black',
        background: 'white',
        highlight: {
          border: 'yellow',
          background: 'orange'
        }
      }
      fontColor: 'red',
      fontSize: 18
    }
    // add more groups here
  }
};

var nodes = [
  {id: 1, label: 'Node 1'},                    // will get the default style
  {id: 2, label: 'Node 2', group: 'mygroup'},  // will get the style from 'mygroup'
  // ... more nodes
];

The following styles are available for groups:

Name Type Default Description
color String | Object Object Color of the node
color.border String "#2B7CE9" Border color of the node
color.background String "#97C2FC" Background color of the node
color.highlight String "#D2E5FF" Color of the node when selected.
color.highlight.background String "#D2E5FF" Background color of the node when selected.
color.highlight.border String "#D2E5FF" Border color of the node when selected.
image String none Default image for the nodes. Only applicable in combination with shape image.
fontColor String "black" Font color of the node.
fontFace String "sans" Font name of the node, for example "verdana" or "arial".
fontSize Number 14 Font size for the node in pixels.
shape String "ellipse" Choose from ellipse (default), circle, box, database, image, label, dot, star, triangle, triangleDown, and square. In case of image, a property with name image must be provided, containing image urls.
radius Number 5 Default radius for the node. Only applicable in combination with shapes box and dot.

Clustering

The graph now supports dynamic clustering of nodes. This allows a user to view a very large dataset (> 50.000 nodes) without sacrificing performance. When loading a large dataset, the nodes are clustered initially (this may take a small while) to have a responsive visualization to work with. The clustering is both outside-in and inside-out. Outside-in means that nodes with only one connection will be contained, or clustered, in the node it is connected to. Inside-out clustering first determines which nodes are hubs. Hubs are defined as the nodes with the top 3% highest amount of connections (assuming normal distribution). These hubs then "grow", meaning they contain the nodes they are connected to within themselves. The edges that were connected to the nodes that are absorbed will be reconnected to the cluster.

A cluster is just a node that has references to the nodes and edges it contains. It has an internal counter to keep track of its size, which is then used to calculate the required forces. The contained nodes are removed from the global nodes index, greatly speeding up the system.

The clustering has the following user-configurable settings. The default values have been tested with the Graph examples and work well. The default state for clustering is off.

Name Type Default Description
enabled Boolean false On/off switch for clustering. It is assumed clustering is enabled in the descriptions below.
initialMaxNumberOfNodes Number 100 If the initial amount of nodes is larger than this value, clustering starts until the total number of nodes is less than this value.
absoluteMaxNumberOfNodes Number 500 While zooming in and out, clusters can open up. Once there are more than absoluteMaxNumberOfNodes nodes, clustering starts until reduceToMaxNumberOfNodes nodes are left. This is done to ensure performance is continiously fluid.
reduceToMaxNumberOfNodes Number 300 While zooming in and out, clusters can open up. Once there are more than absoluteMaxNumberOfNodes nodes, clustering starts until reduceToMaxNumberOfNodes nodes are left. This is done to ensure performance is continiously fluid.
chainThreshold Number 0.4 Because of the clustering methods used, long chains of nodes can be formed. To reduce these chains, this threshold is used. A chainThreshold of 0.4 means that no more than 40% of all nodes are allowed to be a chain node (two connections). If there are more, they are clustered together.
clusterEdgeThreshold Number 20 This is the absolute edge length threshold in pixels. If the edge is smaller on screen (that means zooming out reduces this length) the node will be clustered. This is triggered when zooming out.
sectorThreshold Integer 50 If a cluster larger than sectorThreshold is opened, a seperate instance called a sector, will be created. All the simulation of nodes outside of this instance will be paused. This is to maintain performance and clarity when examining large clusters. A sector is collapsed when zooming out far enough. Also, when opening a cluster, if this cluster is smaller than this value, it is fully unpacked.
screenSizeThreshold Number 0.2 When zooming in, the clusters become bigger. A screenSizeThreshold of 0.2 means that if the width or height of this cluster becomes bigger than 20% of the width or height of the canvas, the cluster is opened. If a sector has been created, if the sector is smaller than 20%, we collapse this sector.
fontSizeMultiplier Number 4.0 This parameter denotes the increase in fontSize of the cluster when a single node is added to it.
forceAmplification Number 0.6 This factor is used to calculate the increase of the repulsive force of a cluster. It is calculated by the following formula: repulsingForce *= 1 + (clusterSize * forceAmplification).
distanceAmplification Number 0.2 This factor is used to calculate the increase in effective range of the repulsive force of the cluster. A larger cluster has a longer range. It is calculated by the following formula: minDistance *= 1 + (clusterSize * distanceAmplification).
edgeGrowth Number 11 This factor determines the elongation of edges connected to a cluster.
clusterSizeWidthFactor Number 10 This factor determines how much the width of a cluster increases in pixels per added node.
clusterSizeHeightFactor Number 10 This factor determines how much the height of a cluster increases in pixels per added node.
clusterSizeRadiusFactor Number 10 This factor determines how much the radius of a cluster increases in pixels per added node.
activeAreaBoxSize Number 100 Imagine a square with an edge length of activeAreaBoxSize pixels around your cursor. If a cluster is in this box as you zoom in, the cluster can be opened in a seperate sector. This is regardless of the zoom level.

Methods

Graph supports the following methods.

Method Return Type Description
setData(data,[disableStart]) none Loads data. Parameter data is an object containing nodes, edges, and options. Parameters nodes, edges are an Array. Options is a name-value map and is optional. Parameter disableStart is an optional Boolean and can disable the start of the simulation that would begin at the end of this function by default.
setOptions(options) none Set options for the graph. The available options are described in the section Configuration Options.
getSelection() Array of ids Returns an array with the ids of the selected nodes. Returns an empty array if no nodes are selected. The selections are not ordered.
redraw() none Redraw the graph. Useful when the layout of the webpage changed.
setSelection(selection) none Select nodes. selection is an array with ids of nodes to be selected. The array selection can contain zero or multiple ids. Example usage: graph.setSelection([3, 5]); will select nodes with id 3 and 5.
setSize(width, height) none Parameters width and height are strings, containing a new size for the visualization. Size can be provided in pixels or in percentages.

Events

Graph fires events after one or multiple nodes are selected. The event can be catched by creating a listener.

Here an example on how to catch a select event. 

function onSelect() {
  alert('selected nodes: ' + graph.getSelection());
}

vis.events.addListener(graph, 'select', onSelect);

The following events are available.

name Description Properties
select Fired after the user selects or unselects a node by clicking it, or when selecting a number of nodes by dragging a selection area around them. Not fired when the method setSelection is executed. The ids of the selected nodes can be retrieved via the method getSelection. none

Data Policy

All code and data is processed and rendered in the browser. No data is sent to any server.