Heatmap | Resource Page | Datylon



What is a heatmap?

A heatmap is a powerful tool for visualizing patterns, trends, and correlations in data. It provides an intuitive way of representing values using colors, making it easy to identify areas of high and low density.

Adding a date or time scale to the x-axis allows you to track changes over time, making it a valuable tool for monitoring trends and identifying anomalies.

But a heatmap is more than just a simple tool for data exploration. It can serve as a foundation for building more complex visualizations that tell a more detailed story. It lets you explore the data and it gives hints on where to look for other outliers, other viewpoints, or specific angles.

By combining a heatmap with other chart types, you can create a multi-layered view of your data that highlights different aspects of its underlying patterns.

A heatmap can have the shape of a table or a matrix or it can function as a color layer over a geographical map. If shaped as a matrix, a heatmap is a perfect way to reveal correlations. A heatmap as an actual map shows the density of a value at a certain place or area.

Heatmaps can also be used in conjunction with other chart types, adding an extra dimension to your visualizations. By coloring charts numerically, you can use the same visualization logic and impact as a ‘regular’ heatmap, providing even more insight into your data.

An example of a heatmap created with Datylon for Illustrator

Variations of heatmaps

The charts below are variations of the heatmap. To learn how to make them with Datylon, check out the heatmap user documentation in our Help Center.
One dimensional heatmap
One dimensional heatmap

One dimensional heatmap

To focus specifically on one category and focus on the evolution of that variable, one can opt for using one-dimensional heatmaps. Heatmaps in a single dimension are commonly used in climate communication and often visualize temperature variations.

Geographical heatmap
Geographical heatmap

Geographical heatmap

If there is a spatial dimension to your data, you can add a color layer to a map. This way, geographical heatmaps can be used to show anything from population density and distribution to weather patterns and the prevalence of diseases in certain regions.

A choropleth map is a variation on the heatmap
A choropleth map is a variation on the heatmap

Choropleth map

While it may appear similar to a geographical heatmap, the two display data differently. In choropleth maps, regions are colored according to geographic or artificial boundaries and represent a proportional value, such as an average, for the delineated area.

Alternatives for a heatmaps

Substitute your heatmap with any of the charts below when you want a visual alternative, that still allows you to explore the data.
Replace your heatmap with parallel coordinates
Replace your heatmap with parallel coordinates

Parallel coordinates

When both dimensions in the data are categorical, we can replace a heatmap with parallel coordinates. Instead of using color to represent value, the parallel coordinate uses the location of the categories on the axis to denote the values.

Replace the heatmap with a bumpchart or another multi-series line chart
Replace the heatmap with a bumpchart or another multi-series line chart

Bump chart or other multi-series line charts

A heatmap data with an evolution dimension is easily transferable to a multi-series line chart. The correlation factor will be lost a bit but instead, you will be able to compare the values between the series much better.

Replace your heatmap with a scatter plot
Replace your heatmap with a scatter plot

Bubble chart

Consider a bubble chart (a beautiful variation of a scatter plot) if you prefer plotting the numerical values more specifically on an axis instead of in bins while still showing correlations in the data. Binding marks to color or size shows value density.

Pro tips for designing a heatmap

Learn how to improve the readability and visual appeal of your heatmap.
The different types of scales for a heatmap

Coloring - 3 types of scales

Choosing the type of scale depends on the type of data that gives color to your heatmap and on the level of detail you want your reader to have. We can choose between a categorical, a numerical sequential or a numerical diverging scale.

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Selecting the right scale for your heatmap

Coloring - numerical or categorical scale

If your data has an order to it, meaning that it is somehow sortable, a numerical scale is the one to go with. If the data is nominal, you should choose a categorical one.

When the data only varies in one direction, a sequential scale is the best choice. When your numerical data has a logical breakpoint and the data varies in two directions, a diverging scale is the way to go.

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Choosing a stepped or a continuous scale for your heatmap

Coloring - stepped or continuous scale

Finally, there is a difference between stepped or continuous scales. With data that is not continuous, but ordinal, you should always go for a stepped scale.

But with continuous data, we can choose what scale we want. Choosing a stepped scale for continuous data helps you make your point more clear and lets your readers derive values more easily. A continuous scale gives a more nuanced view and allows more interpretation up to the reader.

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Sorting your heatmap


Sorting the columns in a tabular heatmap is not always possible.
If your x-axis is numerical or temporal, you cannot sort it at all.
If it is categorical, and there is no order to be followed, sorting it ascending or descending might improve readability. This also goes for the categorical Y-axis.

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Adding data labels to every cell of your heatmap


If you do want to add an extra layer of detail to your heatmap, you can add data labels to every ‘cell’ in the matrix. This also works the other way around. If you have a flat table or data sheet, adding a color layer to the values can instantly help the readability and comprehension of the data.

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Create your own heatmap

Join Datylon for free and get started online or download our Datylon for Illustrator plug-in with a 14-day trial. Connect with a Datylon expert for a demo session.

Heatmap examples & inspiration

Scroll and click on the images below to find inspiration samples of heatmaps. With your Datylon account, you can use these designs, customize them and update them with new data. 

Discover more charts in our Chart Library

Learn more about the different types of charts and graphs you can design with Datylon. Discover other resource pages in our Datylon Chart Library.