malloy-charts

Match the data shape to the renderer: one time column plus a measure uses # line_chart, one category plus a measure uses # bar_chart, aggregates only use # big_value, and two numeric columns use # scatter_chart. The decision tree in the reference maps each shape to a default choice.

Charts render only the first aggregate by default. Use the y property with an array, such as # bar_chart { y=['revenue','cost'] }, to plot multiple measures as series on a single chart.

A top-level chart tag renders only the outer query and silently hides nest views. To display nests, apply # dashboard to the outer query and put chart tags on each nested view definition, not on the nest line.

Malloy has no native pie, donut, treemap, or heatmap renderer. Approximate them with # bar_chart sorted by value for pies, nested ordered tables for treemaps, and # pivot with color values for heatmaps.

The word constructor is reserved in Vega-Lite, which Malloy uses for rendering. If it appears anywhere in the query, rendering fails, so avoid it in queries and as a dimension name in models.

Malloy has no autobin function. Bin manually with arithmetic like floor(price / 20) * 20 in a group_by, choosing the bin width from the column's observed min, max, and percentiles, then render with # bar_chart.