[dumbbell-basic] Basic Dumbbell Chart

[MarkusNeusinger]

Description

A dumbbell chart (also called a connected dot plot or Cleveland dot plot) compares two values for each category using connected dots. It effectively shows the change or difference between two data points, such as before/after comparisons or ranges.

Key Features

• Two dots per category connected by a line
• Clear visualization of change/difference between two points
• More precise than bar charts for showing exact values
• Minimal ink usage for maximum information

Applications

• Before/after comparisons (e.g., performance changes)
• Gap analysis (e.g., salary differences by gender)
• Comparison between two time periods
• Range visualization (min/max values)

Data Requirements

• One categorical variable (labels)
• Two numeric variables (start and end values)
• Works best with 5-20 categories
• Data should show meaningful differences

Visual Elements

• Horizontal or vertical orientation
• Two dots per category (different colors for start/end)
• Connecting line between dots
• Category labels on one axis
• Value scale on other axis

[claude]

✅ Spec ID: dumbbell-basic

Rationale: A dumbbell chart is a distinct plot type that shows two connected values per category, different from lollipop charts (single value per category) already in the repo.

Add label approved to begin generation.

[github-actions]

✅ Specification Ready: dumbbell-basic

PR: #946

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specification.md

dumbbell-basic: Basic Dumbbell Chart

Description

A dumbbell chart (also called a connected dot plot or Cleveland dot plot) compares two values for each category by displaying two dots connected by a line. It effectively visualizes differences, changes, or ranges between two data points such as before/after comparisons, gaps, or min/max values. The connected dots make it easy to see both the magnitude and direction of change.

Applications

• Before/after performance comparisons (e.g., test scores before and after training)
• Gap analysis between groups (e.g., salary differences by department or gender)
• Comparing metrics between two time periods (e.g., Q1 vs Q4 sales by region)
• Displaying ranges such as minimum and maximum values per category

Data

• category (string) - Labels for each comparison group
• start_value (numeric) - The first/left data point value
• end_value (numeric) - The second/right data point value
• Size: 5-20 categories for optimal readability
• Example: Employee satisfaction scores before and after policy changes

Notes

• Horizontal orientation preferred with categories on y-axis and values on x-axis
• Use distinct colors for start and end dots to differentiate the two values
• Sort by difference or one of the values to reveal patterns
• Connecting line should be thin and subtle to not overpower the dots

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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: dumbbell-basic
PR: #946 (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