[bullet-basic] Basic Bullet Chart

[MarkusNeusinger]

Description

A bullet chart displays a single measure against qualitative ranges and a target marker, designed as a space-efficient alternative to gauges. It shows actual performance, target, and performance bands in a compact linear format.

Key Features

• Primary measure shown as a bar
• Target marker as a vertical line
• Background bands showing qualitative ranges (poor/good/excellent)
• Compact design - many can fit on one page

Applications

• KPI dashboards showing actual vs target
• Sales performance against quota
• Project progress against milestones
• Quality metrics with acceptable ranges

Data Requirements

• actual (numeric) - Current/measured value
• target (numeric) - Target or goal value
• ranges (list) - Thresholds for qualitative bands
• Optional: category label for multiple bullets

Visual Elements

• Horizontal or vertical bar for actual value
• Thin vertical/horizontal marker for target
• Shaded background bands (usually 3-5 ranges)
• Grayscale typically for bands to focus on primary measure
• Clear axis with reference scale

[claude]

✅ Spec ID: bullet-basic

Rationale: A bullet chart is a distinct linear chart type designed by Stephen Few as a space-efficient alternative to gauge charts. While gauge-basic exists for circular speedometer-style displays, the bullet chart's horizontal/vertical bar format with target markers and qualitative bands makes it a fundamentally different visualization.

Add label approved to begin generation.

[github-actions]

✅ Specification Ready: bullet-basic

PR: #1018

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specification.md

bullet-basic: Basic Bullet Chart

Description

A bullet chart displays a single measure against qualitative ranges and a target marker, designed by Stephen Few as a space-efficient alternative to gauge charts. The linear format shows actual performance as a bar, a target as a vertical marker, and background bands representing qualitative ranges (poor/satisfactory/good). Its compact design allows multiple bullet charts to fit on a single dashboard for easy comparison across metrics.

Applications

• Displaying sales performance against quarterly quotas in executive dashboards
• Showing project completion percentage against milestone targets in PMO reports
• Comparing actual vs budgeted expenses across departments in financial reviews
• Visualizing quality metrics (defect rates, SLA compliance) against acceptable thresholds

Data

• actual (numeric) - The current/measured value to display as the primary bar
• target (numeric) - The goal or target value shown as a vertical marker line
• ranges (list of numeric) - Thresholds defining qualitative bands (e.g., [50, 75, 100] for poor/satisfactory/good)
• label (string, optional) - Category or metric name for the bullet chart
• Size: Single value display per bullet; multiple bullets can be stacked vertically
• Example: actual = 75, target = 90, ranges = [50, 75, 100] for a KPI at 75% with 90% target

Notes

• Use grayscale shading for background bands to keep focus on the primary measure bar
• The target marker should be a thin contrasting line (often black) perpendicular to the bar
• Horizontal orientation is most common; vertical can be used when space requires it
• Consider adding the actual value as a text label for precise reading
• Multiple bullet charts should align on a common scale when comparing related metrics

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Next: Add approved label to merge this specification to main.

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🤖 spec-create workflow

[github-actions]

🚀 Specification Merged!

Specification: bullet-basic
PR: #1018 (merged)

The specification is now in main and synced to PostgreSQL.

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Next: Add generate:{library} labels to start generating implementations.

Available libraries: matplotlib, seaborn, plotly, bokeh, altair, plotnine, pygal, highcharts, letsplot

Or use workflow dispatch for bulk operations.

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🤖 spec-create workflow