Heatmaps decoded!

Heat maps use color variance for data visualization. They are intensive used for displaying variance between different variables, displaying any particular pattern between them and if any correlation are present between the variables.

• The rows and columns of a table form the matrix structure of the heatmap. Each cell of the matrix contains color coded data or numerical data which is displayed on a color scale. The matrix data represents the relationship between the variables of the row and column associated.
• A legend should be given alongside the heatmap for better understanding of it. Numerical data requires a color scale which has different colors blending into one another to show variance of high and low in the associated data. While categorical data is color coded.
• Heat map uses the color differences to display changes in value, hence it should be used to give a more generalized view of the numerical data. Heatmap should not be used to display sensitive data which needs to be represented accurately.
• Heat maps are best used to show changes in values over time. Any column of row can be used to denote the time changes.
• The colors in the heatmap should be chosen carefully as the difference must be visible immediately to the human eye. Rainbow color schemes are highly used as humans can perceive more shades of those colors. Grey color scales must be avoided as they are difficult for perception.
• The best use of heat maps are done to show temperature changes in a city or town over months or years or to depict the hottest and coolest places to stay.

Source: http://www.datavizcatalogue.com/methods/heatmap.html