@nebula.js/sn-grid-chart
v1.16.10
Published
A grid from two dimensions with symbols of varying size based on a measure.
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Readme
@nebula.js/sn-grid-chart
The grid chart uses symbols of varying size sorted in a grid to visualize a measure across two dimensions. The measure is the metric that determines the size of the symbol in each crossing.
Requirements
Requires @nebula.js/stardust
version 1.2.0
or later.
Installing
If you use npm: npm install @nebula.js/sn-grid-chart
. You can also load through the script tag directly from https://unpkg.com.
Usage
import { embed } from '@nebula.js/stardust';
import gridChart from '@nebula.js/sn-grid-chart';
// 'app' is an enigma app model
const nuked = embed(app, {
types: [
{
// register grid chart
name: 'sn-grid-chart',
load: () => Promise.resolve(gridChart),
},
],
});
// Rendering a simple grid chart
nuked.render({
element: document.querySelector('.grid'),
type: 'sn-grid-chart',
fields: ['Country', 'Year', '=Sum(Population)'],
properties: {
title: 'The historical populations of some European countries',
},
});
More examples
Change symbol size and shape
The size and shape of the symbols can be modified.
// Rendering a grid chart with customized symbols
nuked.render({
element: document.querySelector('.grid'),
type: 'sn-grid-chart',
// fields: ['Country', 'Year', '=Sum(Population)'],
properties: {
title: 'The historical populations of some European countries',
dataPoint: {
rangeBubbleSizes: [0.25, 0.85],
symbol: 'star',
},
},
});
Customize the look of the chart
You can color the symbol by measure and add a legend to show more information about the measure. The axis titles can be hidden and the gridlines can be shown to further improve the look.
// Rendering a customized grid chart
nuked.render({
element: document.querySelector('.grid'),
type: 'sn-grid-chart',
// Define all `fields` in `properties`
properties: {
title: 'The historical populations of some European countries',
qHyperCubeDef: {
qDimensions: [
{
qDef: { qFieldDefs: ['Country'] },
},
{
qDef: { qFieldDefs: ['Year'] },
qAttributeExpressions: [
{
qExpression: 'Sum(Population)',
id: 'colorByAlternative',
},
],
},
],
qMeasures: [
{
qDef: {
qDef: 'Sum(Population)',
},
},
],
qMode: 'T',
qAlwaysFullyExpanded: true,
},
color: {
auto: false,
mode: 'byMeasure',
measureScheme: 'dg',
reverseScheme: true,
},
legend: {
show: true,
dock: 'auto',
showTitle: true,
},
xAxis: {
show: 'label',
dock: 'near',
gridLines: true,
},
yAxis: {
show: 'label',
dock: 'near',
gridLines: true,
},
},
});
Grid chart plugins
A plugin can be passed into a grid chart to add or modify its capability or visual appearance. A plugin needs to be defined before it can be rendered together with the chart.
// Step 1: define the plugin
// Modifying the look of the existing point component
const pointPlugin = {
info: {
name: 'point-plugin',
type: 'component-definition',
},
fn: ({ layout, keys }) => {
const componentDefinition = {
type: 'point',
// Provide the same name as the exisiting point component to override it
key: keys.COMPONENT.POINT,
settings: {
strokeWidth: '2px',
stroke: 'dimgray',
// Using data property 'd' and layout as input for helper functions
size: (d) => getSizeInLogarithmScale(d, layout),
fill: (d) => getColorBasedOnMedian(d),
},
};
return componentDefinition;
},
};
// Step 2: passing the plugin definition into the render function
// Rendering a grid chart with plugins
nuked.render({
element: document.getElementById('object'),
type: 'sn-grid-chart',
fields: ['Country', 'Year', '=Sum(Population)'],
plugins: [pointPlugin],
properties: {
title: 'The historical population of some European countries',
xAxis: { show: 'labels', gridLines: true },
yAxis: { show: 'labels', gridLines: true },
},
});
The plugin definition is an object, with two properties info
and fn
.
The fn
returns a picasso.js
component. To build this component,
some important chart internals are passed into the argument object of fn
.
// Structure of the argument object of fn
const pluginArgs = {
layout,
keys: {
SCALE: {
X,
Y,
},
COMPONENT: {
X_AXIS,
Y_AXIS,
POINT,
},
COLLECTION: {
MAIN,
},
},
};
With plugins, you can either add new components or modify existing components of the grid chart.
Add new components
The new component can be a standard Picasso component or a custom Picasso component. Here we demo a custom component which add labels next to the grid bubbles.
// Implementing a custom labels plugin, so that we can use it later
const labelsPluginDefinition = {
info: {
componentName: 'custom-labels-plugin',
name: 'custom-labels-plugin',
type: 'custom-component',
},
fn: () => {
const implementation = {
require: ['chart', 'renderer'],
render() {
const { items } = this.chart.component('point-component').data;
const scale = this.chart.scales();
const { width, height } = this.rect;
const labels = items.map((item) => ({
type: 'text',
text: item.size.label,
x: (scale.x(item.x.value) + scale.x.bandwidth() * 0.5) * width,
y: (scale.y(item.y.value) + scale.y.bandwidth() * 0.2) * height,
anchor: 'middle',
fill: 'dimgray',
}));
return labels;
},
};
return implementation;
},
};
// Using the labels plugin, defined above
const labelsPlugin = {
info: {
name: 'labels',
type: 'component-definition',
},
fn: ({ keys }) => {
const componentDefinition = {
// The type has to match with the componentName of the labels plugin definition above
type: 'custom-labels-plugin',
key: 'my-labels',
};
return componentDefinition;
},
};
Modify existing components
As an example, the positions and the appearance of the axes can be modified completely by plugins.
To overide an existing component, fn
should returns a picasso.js
component
that has the same key
as the existing component (keys.COMPONENT.X_AXIS
in
this example)
// Modifying the look and the position of the x-axis
const xAxisPlugin = {
info: {
name: 'x-axis-plugin',
type: 'component-definition',
},
fn: ({ keys, layout }) => {
const componentDefinition = {
type: 'axis',
// Provide the same name as the exisiting x-axis component to override it
key: keys.COMPONENT.X_AXIS,
layout: { dock: 'top' },
settings: {
labels: {
fontFamily: 'Cambria, serif',
fontSize: '15px',
fill: 'dimgray',
},
line: { stroke: 'gray' },
},
};
return componentDefinition;
},
};
// y-axis plugin can be defined with similar code
// ...
Plugins disclaimer
- The plugins API is still experimental.
- We can not guarantee our charts to be compatible with all different settings, especially when modifying existing components.