A Beginner’s Guide To D3 Heat Map

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Sencha D3 JavaScript is fully integrated with Ext JS, allowing you to generate rich data visualizations quickly and include them in any Ext JS web application.

The D3 package contains many component types, such as treemaps, D3 heat maps, and pivot heatmaps. Read on to explore more about the D3 heat map.

What is D3?

A Beginner’s Guide To D3 Heat Map D3 (Data-Driven Documents) is a powerful JavaScript library packed with features. It lets you build interactive and dynamic data visualizations right in the browser using modern web standards like HTML, SVG, and CSS. Best of all, D3 is free and open-source, so you can use it without any cost.

Rather than a bulky all-in-one framework, D3 focuses on the core challenge of data-driven document manipulation. By avoiding proprietary formats, it delivers exceptional flexibility and lets web standards such as HTML, SVG, and CSS truly shine.

D3 is lightning-fast with minimal overhead. It effortlessly handles large datasets and supports smooth interactivity and animations. Its functional style also promotes code reuse through a rich ecosystem of official and community-built components.

What Is A D3 Heat Map?

The ‘d3-heatmap’ component displays matrices where individual values are represented by colors. The component uses two Ext.d3.axis instances—one for the data axes and another as a single Ext.d3.axis—while values are encoded via a color axis.

Heat maps excel at presenting three-dimensional information within a two-dimensional view. As expected, the heat map element maps X and Y data to the respective axes, then maps Z values to a ‘color axis.’

How Does Theming Work?

A Beginner’s Guide To D3 Heat Map Themes play a vital role in charts by helping users distinguish different data series. D3 heat maps fully support theming, which works consistently with other Ext JS components.

The main exception involves heat map cell and tree node colors, which require Ext.d3.axis to render a color range (for example, from white to red). In this setup, white can represent the lowest performance and red the highest, as shown in the code below.

colorAxis: {
field: ‘performance’,
scale: {
type: ‘linear’,
range: [‘white’, ‘orange’]
}
}

What Are The Events In D3?

Events can fire at various stages of a chart’s life cycle. D3 provides its own system for handling node events, yet it is not compatible with Ext JS’s event system.

Touch events are not automatically mapped to desktop events (and vice versa) within the D3 event system. For this reason, it is best to avoid using that system directly. Instead, use one of the approaches below.

Each Method

selection.each(function (node) {
Ext.fly(this).on(‘click’, handlerFn, scope);
});

Fly Method

Ext.fly(selection.node()).on(‘click’, handlerFn, scope);

Preferred Method

var element = Ext.get(me.getScene().node());

element.on(‘click’, handlerFn, scope, {
delegate: ‘g.x-class-name’
});

What Are The Interactions Supported In A D3 Heat Map?

A Beginner’s Guide To D3 Heat Map Interactions are essential for letting end users explore chart data. D3 components introduce the ‘interaction’ concept instead of relying on D3’s native ‘behaviors.’

Ext.d3.interaction.PanZoom is currently the only supported interaction. It replaces and enhances D3’s ‘zoom’ behavior while adding support for limited kinetic scrolling, panning, scroll indicators, and the Ext JS event system—features the original PanZoom interaction addresses.

Can I Add Tooltips?

Tooltips appear when users hover over data points, making it easy to identify values in charts with large datasets. The Ext.d3.mixin supports the ‘tooltip’ config across all enhanced components via the Ext.d3.mixin.ToolTip mixin. The configuration matches other Ext JS components, with one extra property: ‘renderer.’

The renderer is typically the only piece you need to implement when creating a tooltip. Two methods are available, as shown below.

View Controller Method

tooltip: { // inside a view’s D3 component configuration
renderer: ‘tooltip’
}

// handler

tooltip: function (comp, tooltip, node, element, event) {
var x = node.childNodes.length;
tooltip.setHtml(x + ‘ items’ + (x === 1 ? “” : ‘s’) + ‘ inside.’);
}

View Method

tooltip :
renderer: function(comp, tooltip, record) {
tooltip.setHtml(record.get(‘text’));
}
}

Is Pivoting Possible?

A Beginner’s Guide To D3 Heat Map Pivot charts offer an effective way to present data visually and simplify analysis. A Pivot Matrix can also integrate local data. The latest ‘pivot-d3’ package includes several key components that combine these capabilities for you.

When working with heat maps, Ext.pivot.D3.HeatMap is available in the package. It generates only a D3 heat map, so only one dimension per axis should be specified.

What Does The D3 Adapter Do?

The D3 Adapter enables you to bring powerful Data-Driven Documents (D3) visualizations—such as heat maps, sunbursts, and treemaps—into your web applications. Users can create dynamic visuals that tell a story, helping others explore data and uncover the insights it holds.

Which Features Does Sencha Offer?

Sencha Charts is a robust library for building charts in Sencha Touch and Ext JS applications. It is designed and optimized for full compatibility with touch gestures and mobile devices, making data visualizations effortless.

Combined with D3, Sencha also delivers advanced visualizations such as treemaps and heat maps, delivering even greater value to end users.

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