Source code in 15 libraries — Python: Altair, Bokeh, lets-plot, Matplotlib, Plotly, plotnine, Pygal, Seaborn; R: ggplot2; Julia: Makie.jl; JavaScript: Chart.js, D3.js, Apache ECharts, Highcharts, MUI X Charts.
A heatmap displaying values in a matrix format using color intensity. Each cell's color represents the magnitude of the value, making it easy to identify patterns, clusters, and outliers in two-dimensional data. Essential for visualizing correlations, frequencies, and relationships between variables.

Preview render from the Altair implementation.