Complex charts
Complex charts are a powerful way to display complex data sets. While less intuitive than basic charts, the visualizations should still tell a story the user can understand.
- Alluvial/sankey diagrams
- Heat maps
- Network diagrams
- Parallel coordinates
- Tree diagrams
- Tree maps
- Circle packs
- Geospatial charts
Alluvial/sankey diagrams
Alluvial, or Sankey diagrams, are a type flow diagram designed to show two indicators of a dataset and how records distribute among them, highlighting correlations.
Multiple blocks of two indicators can be placed next to each other creating a wider alluvial diagram but it’s crucial to consider that this specific kind of chart does not show correlations between indicators that are not directly connected. This is usually emphasized using a different set of colors for each block.
Heat maps
A heat map is a two-dimensional visualization in which individual values contained in a matrix are represented as colors. This technique makes it easy to visualize complex data at a glance. When it comes to heat maps, the most common color ranges are expressed in either sequential and diverging color scales according to the type of data represented.
Sequential scales
Sequential scales use a blended progression, typically of a single color, from the lowest contrast to the highest contrast values, representing lows to highs. It’s best practice to use a sequential scale with values that are all positive or all negative. Sequential heat maps can leverage the full range of the palette (from 10–100) to maximize contrast. Please note that the 3:1 minimum contrast requirement does not apply to heat maps.