Heatmap Generator Heatmaps

Common Types of Heatmaps

• Correlation matrix — shows relationships between variables with diverging color scales
• Calendar heatmap — displays daily values across weeks and months (GitHub-style)
• Gene expression heatmap — visualizes expression levels across genes and conditions with clustering
• Confusion matrix — evaluates classification model performance with predicted vs actual labels
• Geographic heatmap — shows spatial data intensity on maps
• Temporal heatmap — displays patterns by hour, day, or season for time-series analysis

Heatmap Design Best Practices

Choose the right color scale: sequential (one color gradient) for single-direction data, diverging (two-color) for data with a meaningful midpoint. Annotate cell values when the matrix is small enough to read. Add clustering dendrograms for exploratory analysis. Include a clear color legend with value labels. Keep axis labels readable and avoid overcrowding by limiting the matrix size or using abbreviations.

When to Use a Heatmap

Use heatmaps when you need to visualize patterns in matrix-shaped data. They excel at showing correlations between many variables simultaneously, temporal patterns across two time dimensions, performance across multiple categories, and clustering patterns in biological data. Avoid heatmaps when you need precise value comparison — bar charts or tables are better for that. Heatmaps are strongest when the overall pattern matters more than individual values.