feat(pygal): implement range-interval

[github-actions]

Implementation: range-interval - pygal

Implements the pygal version of range-interval.

File: plots/range-interval/implementations/pygal.py

Parent Issue: #3577

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🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

The plot displays a range interval chart showing monthly temperature ranges across 12 months (Jan-Dec). Each month is represented by a blue (#306998) floating bar that spans from the minimum to maximum temperature for that month. The y-axis shows "Temperature (°C)" ranging from -2 to 28, and the x-axis shows "Month" with abbreviated month labels. The title correctly reads "range-interval · pygal · pyplots.ai" at the top. A legend at the bottom displays "Temperature Range (°C)". Horizontal grid lines are visible at 2-degree intervals. The bars effectively show the seasonal pattern with narrow ranges in winter months (Jan: -2 to 6°C, Feb: 0 to 8°C) and wider, higher ranges in summer (Jul: 19 to 28°C). The overall layout is clean with good use of whitespace.

Quality Score: 91/100

Criteria Checklist

Visual Quality (36/40 pts)

• VQ-01: Text Legibility (9/10) - Title and axis labels are clearly readable. Font sizes are appropriate for the canvas size. Tick labels slightly small but still legible.
• VQ-02: No Overlap (8/8) - No overlapping text elements. Month labels are well-spaced.
• VQ-03: Element Visibility (7/8) - Bars are clearly visible with good sizing. Could benefit from slightly more contrast or edge highlighting.
• VQ-04: Color Accessibility (5/5) - Single blue color scheme is colorblind-safe. Good contrast against white background.
• VQ-05: Layout Balance (5/5) - Plot fills canvas well with balanced margins. Good use of space.
• VQ-06: Axis Labels (2/2) - Descriptive labels with units: "Temperature (°C)" and "Month".
• VQ-07: Grid & Legend (0/2) - Legend placement at bottom is acceptable but the invisible series creates a gap. Grid is subtle but works.

Spec Compliance (23/25 pts)

• SC-01: Plot Type (8/8) - Correct range interval chart implementation using stacked bar technique.
• SC-02: Data Mapping (5/5) - Categories on x-axis, range values on y-axis as specified.
• SC-03: Required Features (4/5) - Shows min-max ranges effectively. Missing optional endpoint markers mentioned in spec notes.
• SC-04: Data Range (3/3) - Y-axis range appropriately shows all data from -2 to 28.
• SC-05: Legend Accuracy (2/2) - Legend correctly identifies the temperature range.
• SC-06: Title Format (1/2) - Title uses correct format but uses regular dot (·) which displays correctly.

Data Quality (19/20 pts)

• DQ-01: Feature Coverage (7/8) - Shows variation in range sizes across seasons. Winter months have narrow ranges, summer months have wider ranges. Good seasonal pattern.
• DQ-02: Realistic Context (7/7) - Monthly temperature ranges for a temperate climate location. Realistic and neutral scenario.
• DQ-03: Appropriate Scale (5/5) - Temperature values are realistic for a temperate European climate.

Code Quality (10/10 pts)

• CQ-01: KISS Structure (3/3) - Simple script structure: imports → data → chart config → save. No functions or classes.
• CQ-02: Reproducibility (3/3) - Data is deterministic (hardcoded values), no randomness.
• CQ-03: Clean Imports (2/2) - Only pygal and Style imported, both are used.
• CQ-04: No Deprecated API (1/1) - Uses current pygal API.
• CQ-05: Output Correct (1/1) - Saves as plot.png and plot.html.

Library Features (3/5 pts)

• LF-01: Distinctive Features (3/5) - Uses pygal's StackedBar with custom Style effectively. The invisible base bar technique is clever. Could use more pygal-specific features like tooltips or animation.

Strengths

• Clever implementation using stacked bar with invisible base to create floating range bars
• Clean, professional appearance with good color choice
• Realistic temperature data showing clear seasonal variation
• Proper title format and axis labels with units
• Good canvas utilization and layout balance

Weaknesses

• Grid & legend could be improved - the invisible series technique leaves legend slightly awkward
• Missing optional endpoint markers at min/max points as suggested in spec notes
• Could leverage more pygal-specific interactive features

Verdict: APPROVED