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Chart Types

Canvas supports all major Apache ECharts chart types. Your canvas agent selects the optimal type automatically based on the data and your prompt — or you can specify a type hint explicitly.

Supported Types​

Horizontal Bar​

Type hint: horizontal_bar

Best for: ranked lists, comparisons with more than 5 categories.

  • Categories on the y-axis, sorted descending by value
  • Labels shown on bars for ≤20 bars
  • Default choice for most categorical comparisons

Vertical Bar​

Type hint: bar

Best for: a small number of discrete groups (fewer than 6).

  • Categories on the x-axis
  • Use when category names are short

Line​

Type hint: line

Best for: time series, trends over time.

  • Smooth curves for dense data
  • Supports multiple series for metric comparison over time

Scatter​

Type hint: scatter

Best for: correlations between two numeric fields.

  • Each point is one data record
  • Use when you want to see clustering or outliers

Heatmap​

Type hint: heatmap

Best for: a grid of category × category comparisons (e.g., device × severity, day × hour).

  • Requires a visualMap component (color scale legend)
  • Higher intensity = higher value

Pie / Donut​

Type hint: pie

Best for: proportional breakdown with 6 or fewer categories.

  • Donut style (inner radius 40%, outer 70%)
  • Automatically falls back to horizontal bar when more than 6 categories are present

Treemap​

Type hint: treemap

Best for: hierarchical proportions (parts of a whole with sub-categories).

  • Rectangle area = value
  • Color by category or value

Sunburst​

Type hint: sunburst

Best for: two-level hierarchies.

  • Inner ring = parent category, outer ring = child
  • Use when you have nested group → sub-group data

Box Plot​

Type hint: box

Best for: distributions — showing min, Q1, median, Q3, max.

  • One box per category
  • Good for comparing distributions across groups

Parallel Coordinates​

Type hint: parallel

Best for: comparing records across 4 or more numeric dimensions simultaneously.

  • Each line is one record
  • Axis scales are independent

Gauge​

Type hint: gauge

Best for: a single KPI value as a speedometer.

  • One number, displayed prominently
  • Use for completion rates, scores, percentages

Type Hints​

You can specify a type hint in your prompt to force a particular chart type:

"Show the top 10 error codes as a horizontal bar chart"

Or use the type selector in the auto-generate plan review to override the agent's choice for individual charts.

Label Length Rule​

Axis labels and legend items are automatically truncated to 20 characters. If your data contains long strings (e.g., full sentences from a message field), the canvas agent is instructed to group them into short thematic labels (e.g., "Access Denied", "Rate Limited") rather than using the raw text.

Tooltip Drilldown​

When a bar or slice value represents a count of distinct items (not a sum or average), the tooltip shows a purple pill list of the contributing items on hover. This is generated automatically by the canvas agent when it detects count-based data.

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