80 types of charts for data visualization. Part 6: Geospatial & other charts
by Ivan Kilin — Data Visualization Specialist & Dieuwertje van Dijk — Data Visualization Designer @
Recently we’ve rewritten our essential article about 80 types of charts. Our main goal was to make the information structured and helpful right away. We talk about every chart starting from the look and feel and then going into practical advice on when you should and when you shouldn’t use this particular chart type. We are publishing parts of this article here. One chart group per each article.
In the sixth part, we’ll talk about geospatial visualization and other graphs types. Keep on reading!
Geographic heatmap
Alternative names: hot spot map, geo heat map, density heatmap
What is a geographic heatmap?
A geographic heatmap is a geographical representation of data that demonstrates where something occurs, specifying the areas of data’s high and low density. Geo heatmap does not limit displaying geospatial data to specified boundaries. Therefore, using the data’s location radius, it can cover a small and specific geographic area, as well as large regions, such as oceans or coasts. It uses color to highlight the areas of occurrence.
When should you use a geographic heatmap?
A geographic heatmap helps to understand the distribution and density of the given parameter on a map. The obvious application of geo heatmaps is weather forecasting, but there are many more spheres where it can be used: real estate, commerce, transportation, healthcare, environmental science, and many more.
When you shouldn’t use a geographic heatmap
Geographical heatmaps have the same core drawbacks as regular heatmaps. It gives an approximate view and can lack important details. Extremes can dominate, which can sometimes be misleading. You should also take into consideration that geo heatmaps heavily rely on colors. This means you should be really attentive to color palettes and take color blind viewers into consideration while designing it.
Choropleth map
What is a choropleth map?
A choropleth map is a type of map in which different administrative areas are colored (or shaded) according to the magnitude of their numeric value. The main difference between a choropleth map and a geographic heatmap is that a choropleth map uses border-defined areas, such as countries, states, or neighborhoods.
When should you use a choropleth map?
Choropleth maps display geographical data using normalized values, making them ideal for illustrating various rates and ratios across different regions.
When you shouldn’t use a choropleth map
Choropleth maps can be misleading when used to display raw data that is in some way connected to population. If a region has a high population, it might automatically show high absolute values for population-related indicators. That’s why it’s important to use per-capita values for choropleth maps.
Sometimes, the size of the geographical area can be misleading, either increasing or decreasing the perceived importance of the region. To minimize this influence, you could consider alternatives such as tile maps, where all regions are represented by icons of the same size.
Tile map
What is a tile map?
A tile map is a type of geographical map where a larger area (usually a country or a continent) is visualized by multiple equal-sized and shaped tiles, often square rectangles. Each tile represents a different region. A simple example of a tile map can be a collection of tiles forming the shape of the United States, where each tile corresponds to a state. What is important about tile maps is that all tiles do not vary in size, meaning that larger regions cannot dominate the visualization and smaller regions are not harder to read.
When should you use a tile map?
When the size of a geographical region is not relevant or might introduce a biased perception, a tile map is a perfect solution. Tile maps are also effective due to their clear structure and gridded view.
When you shouldn’t use a tile map
In cases where the shape of the geographical region is important, tile maps should be replaced by regular or choropleth maps.
Chord diagram
What is a chord diagram?
A chord diagram is used to show the structure of paired connections between the instances of the same level. Every instance is represented by an arc. Every connection is shown as a band with (potential) various start and end widths to depict differences in input and output.
When should you use a chord diagram?
Chord diagrams work well for showing the connection and the magnitude of the connection between the categories. It can reveal complex relationships that might be hard to find with other chart types. Common examples of chord diagrams vary from international trade flows to text and script analysis.
When you shouldn’t use a chord diagram
Chord diagrams might not work that well with large datasets and many connections. Many connections on the chord diagram might look busy and confusing.
Arc diagram
What is an arc diagram?
An arc diagram, in its essence, is similar to a chord diagram. While the chord diagram focuses mostly on the quantitative aspect of the connection, the arc diagram is more focused on the existence of the link. In an arc diagram, nodes are placed along a single baseline, and connections are drawn as arcs between them.. Arcs could be placed above and below the baseline, showing a different attribute of the connection.
Although the focus of the arc diagram is to show the existence of the connection, it can also be used to show the quantitative aspect of the connection using the thickness of the arc.
When should you use an arc diagram?
Arc diagrams are used for showing connections between pairs of categories. It allows us to see the structure of connections in a visual way.
When you shouldn’t use an arc diagram
Arc diagrams can be confusing to read if the dataset is too large. A lot of connection arcs can make the chart look cluttered and really hard to read.
Sankey
What is a sankey?
A Sankey diagram is a type of visualization that allows you to display flows from one set of values to another. It shows entities that represent the values and connects them by links, or flows. Each flow has a varying height, which depends on its quantity.
When should you use a sankey?
Sankey diagrams are commonly used to visualize supply chains, engineering and production processes, and energy efficiency. A known example is Google Analytics, which uses Sankey diagrams to depict the customer journey between pages of a website.
When you shouldn’t use a sankey
Sankey diagrams can be very difficult to interpret if the data is complex and the number of nodes and flows is extensive, making it hard to follow the flow. Additionally, they can fail when a precise comparison is needed. While visually appealing, Sankey diagrams can be challenging to interpret, and the audience will likely require an introduction to read them properly.
Network diagram
Alternative names: Network graph, Network mapping, Network visualization
What is a network diagram?
A network diagram is used to show the connections between multiple elements. The structure of the data and the purpose are somewhat similar to the arc diagram. But while in the arc diagram, all of the points are placed on the same line, in the network diagram positioning of the peaks can vary. In some variations of the network diagram, the position of the point depends on the number of connections this point has and the group it belongs to.
When should you use a network diagram?
Network diagrams are often used to show the clusters of members based on the intensity of the connections. Network diagrams are effective for showing patterns, clusters, and hierarchical relationships. All these types of connections are really hard to grasp all at once using any other chart.
When you shouldn’t use a network diagram
Network diagrams can also fail to be useful or meaningful in case the data lacks structure. They can easily become too crowded and complex if there are too many nodes and edges.
Flowchart
What is a flowchart?
A flowchart is a visualization of a workflow. It’s a diagram that depicts subsequent steps in the process. In other words, it shows what steps need to be followed to complete an action. A flowchart uses connecting lines and arrows to allow viewers to follow the process.
When should you use a flowchart?
A flowchart has many organizational use cases and can be a good tool to map out the customer journey and step-by-step instructions. It’s also popular in project management.
When you shouldn’t use a flowchart
A flowchart works best for simple structures. If you need to visualize a complex process or a large dataset, a flowchart is not the best choice.
That’s it for our 6 part series about chart types. Hope you enjoyed it. If you haven’t checked our previous parts you can find them here:
Part 1: Comparison charts
Part 2: Correlation charts
Part 3: Part-to-whole charts
Part 4: Data-over-time charts
Part 5: Distribution charts
