02·Chart types — when to use line, bar, scatter, hist, box, heatmap

Introduction

Picking a chart type is a semantic decision, not an aesthetic one — each type encodes a different kind of relationship in the data. The lesson systematises when to use a line (continuity, time), bars (comparison of discrete categories), scatter (relation between two continuous variables), histogram (single-variable distribution), boxplot/violin (per-group distribution), heatmap (2D matrix). It surfaces pitfalls: pie charts on 8 categories, the "jet" colormap, missing vmin/vmax on heatmaps, confusing histograms with bar charts. After it you will pick the chart for the data, not the other way around.