feat(pygal): implement histogram-stacked

[github-actions]

Implementation: histogram-stacked - pygal

Implements the pygal version of histogram-stacked.

File: plots/histogram-stacked/implementations/pygal.py

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🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

The plot displays a stacked bar chart simulating a stacked histogram of plant height measurements in centimeters. Three groups are shown: Shade-grown (blue, #306998), Partial-sun (yellow, #FFD43B), and Full-sun (green, #4CAF50). The x-axis displays 12 bin ranges from "5-10" to "60-65" cm with the label "Plant Height (cm)". The y-axis shows "Frequency" ranging from 0 to approximately 80. The title correctly reads "histogram-stacked · pygal · pyplots.ai" at the top center. The legend is positioned in the top-left corner showing all three group labels. The bars are properly stacked, with the blue (Shade-grown) distribution centered around 20-30 cm, yellow (Partial-sun) around 30-40 cm, and green (Full-sun) around 40-50 cm. The overall layout is clean with a white background and subtle horizontal grid lines.

Quality Score: 91/100

Criteria Checklist

Visual Quality (36/40 pts)

• VQ-01: Text Legibility (9/10) - Title, axis labels, and tick labels are all readable. Font sizes are appropriate for the 4800x2700 canvas. Legend text is slightly small but still legible.
• VQ-02: No Overlap (8/8) - No overlapping text elements. X-axis labels are well-spaced.
• VQ-03: Element Visibility (8/8) - Bars are well-sized and clearly visible. Stacking is clearly distinguishable.
• VQ-04: Color Accessibility (4/5) - Blue, yellow, and green provide good contrast. Not a red-green combination, but blue-yellow-green could be slightly improved for deuteranopia.
• VQ-05: Layout Balance (5/5) - Plot fills canvas well with balanced margins. Legend is appropriately positioned.
• VQ-06: Axis Labels (2/2) - X-axis has "Plant Height (cm)" with units, Y-axis has "Frequency".
• VQ-07: Grid & Legend (0/2) - Grid lines are subtle (good), but legend placement in top-left corner overlaps with the plot area slightly and could be better positioned.

Spec Compliance (25/25 pts)

• SC-01: Plot Type (8/8) - Correctly implements stacked histogram using pygal's StackedBar chart.
• SC-02: Data Mapping (5/5) - X shows bin ranges, Y shows frequency, stacking shows group contributions.
• SC-03: Required Features (5/5) - All spec features present: stacked bars, distinct colors, legend with group labels, same bin boundaries for all groups.
• SC-04: Data Range (3/3) - All data visible within the chart bounds.
• SC-05: Legend Accuracy (2/2) - Legend labels correctly show "Shade-grown", "Partial-sun", "Full-sun".
• SC-06: Title Format (2/2) - Title follows exact format: "histogram-stacked · pygal · pyplots.ai".

Data Quality (18/20 pts)

• DQ-01: Feature Coverage (7/8) - Shows three distinct distributions with different means and spreads. Could benefit from more overlap between groups to better demonstrate stacking.
• DQ-02: Realistic Context (7/7) - Plant growth measurements under different sunlight conditions is a realistic, neutral scientific scenario.
• DQ-03: Appropriate Scale (4/5) - Plant heights of 5-65 cm are reasonable, though the distributions could have more natural variation.

Code Quality (10/10 pts)

• CQ-01: KISS Structure (3/3) - Clean linear structure: imports → data → chart config → save.
• CQ-02: Reproducibility (3/3) - Uses np.random.seed(42).
• CQ-03: Clean Imports (2/2) - Only necessary imports: numpy, pygal, Style.
• 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 (2/5 pts)

• LF-01: Distinctive Features (2/5) - Uses pygal's StackedBar and custom Style, but doesn't leverage more distinctive pygal features like tooltips configuration or value formatters.

Strengths

• Excellent implementation of stacked histogram concept using pygal's StackedBar
• Clean, well-organized code following KISS principles
• Realistic plant growth scenario with meaningful group labels
• Proper title format and axis labels with units
• Good color palette with sufficient contrast between groups
• Appropriate use of custom Style for consistent theming

Weaknesses

• Legend position in top-left corner could be moved to avoid proximity to plot area (consider legend_at_bottom=True or repositioning)
• Could leverage more pygal-specific features like custom tooltips or value labels

Verdict: APPROVED