This heat map would show how temperature changed over the years in each month. For example, one dimension might represent year, and the other dimension might represent month, and the value measured might be temperature. Color ranges from blue (cold) to red (hot).Ī grid heat map displays magnitude as color in a two-dimensional matrix, with each dimension representing a category of trait and the color representing the magnitude of some measurement on the combined traits from each of the two categories. In the image labeled “Spatial Heat Map Example,” temperature is displayed by color range across a map of the world. There are two main type of heat maps: spatial, and grid.Ī spatial heat map displays the magnitude of a spatial phenomena as color, usually cast over a map. Spatial Heat Map Example: Displays temperature across a world image with red being the highest and blue being the lowest degree in temperatures (5 April 2019). The company that acquired Kinney's invention in 2003 unintentionally allowed the trademark to lapse. Software designer Cormac Kinney trademarked the term 'heat map' in 1991 to describe a 2D display depicting financial market information. display shown in the figure is a replication of the earlier SYSTAT design. Leland Wilkinson developed the first computer program in 1994 ( SYSTAT) to produce cluster heat maps with high-resolution color graphics.

Ling used overstruck printer characters to represent different shades of gray, one character-width per pixel. The idea for joining cluster trees to the rows and columns of the data matrix originated with Robert Ling in 1973. Jacques Bertin used a similar representation to display data that conformed to a Guttman scale. Sneath (1957) displayed the results of a cluster analysis by permuting the rows and the columns of a matrix to place similar values near each other according to the clustering. Toussaint Loua (1873) used a shading matrix to visualize social statistics across the districts of Paris.

Larger values were represented by small dark gray or black squares (pixels) and smaller values by lighter squares. Heat maps originated in 2D displays of the values in a data matrix. 'Heat map' is a relatively new term, but the practice of shading matrices has existed for over a century. By contrast, the position of a magnitude in a spatial heat map is forced by the location of the magnitude in that space, and there is no notion of cells the phenomenon is considered to vary continuously. The size of the cell is arbitrary but large enough to be clearly visible. In a cluster heat map, magnitudes are laid out into a matrix of fixed cell size whose rows and columns are discrete phenomena and categories, and the sorting of rows and columns is intentional and somewhat arbitrary, with the goal of suggesting clusters or portraying them as discovered via statistical analysis. There are two fundamentally different categories of heat maps: the cluster heat map and the spatial heat map. The variation in color may be by hue or intensity, giving obvious visual cues to the reader about how the phenomenon is clustered or varies over space. A heat map showing the RF coverage of a drone detection systemĪ heat map (or heatmap) is a data visualization technique that shows magnitude of a phenomenon as color in two dimensions.

Visualize synonym