Heat map
A data visualization technique using color to represent magnitude.
A heat map (or heatmap) is a two-dimensional data visualization technique that represents the magnitude of individual values within a dataset as a color. The variation in color may be by hue or intensity. In some applications such as crime analytics or website click-tracking, color is used to represent the density of data points rather than a value associated with each point. 'Heat map' is a relatively new term, but the practice of shading matrices has existed for over a century.
- earliest_example_creator
- Toussaint Loua
- term_coined_by
- Cormac Kinney
- field
- Data visualization
Lore & Background
Heat maps originated in 2D displays of the values in a data matrix. Larger values were represented by small dark gray or black squares (pixels) and smaller values by lighter squares. In 1950, Louis Guttman developed the Scalogram, a method for ordering binary matrices to expose a one-dimensional scale structure. Ling used overstruck printer characters to represent different shades of gray, one character-width per pixel. The Eisen et al. display shown in the figure is a replication of the earlier SYSTAT design.
Reader's Guide
Heat maps are significant as a versatile data visualization tool used across many fields. They simplify complex datasets by representing magnitude as color, making patterns and clusters immediately visible. There are two primary categories: spatial heat maps, which display magnitude of a spatial phenomenon as color over a map, and grid heat maps, which display magnitude as color in a two-dimensional matrix. Grid heat maps are further categorized into clustered heat maps and correlograms. Applications include business analysis, website analysis (mouse tracking, eye tracking, click tracking, AI-generated attention, scroll tracking), exploratory data analysis, biology (DNA, RNA, gene expression), financial analysis, geographical visualization, sports, and cybersecurity. The technique allows users to detect clustering, compare performers, and visualize geographic distributions.
Did You Know?
- In a correlogram, the combination of A-B is the same as B-A, so it is displayed as a triangle instead of a square.
Frequently Asked Questions
What is a Heat map?
A Heat map is a two-dimensional data-visualization method that encodes the magnitude of individual values in a dataset using color, whether through shifts in hue or changes in intensity.
What are Heat map's core 'powers' or roles in practice?
It translates numeric magnitude into a color gradient so viewers can spot patterns at a glance, and in applied settings like crime analytics or website click-tracking it can instead encode the density of data points rather than a single value per cell.
More in Map Projections & Cartography Foundations 1-24
Elsewhere in the Map Projections & Cartography Foundations universe
Spotted an error? Know more?
This is a living reference — every entry is fact-audited, and reader corrections feed straight into our audit queue. Suggest an edit · See this site's audit record