feat(pygal): implement scatter-basic

[github-actions]

Implementation: scatter-basic - python/pygal

Implements the python/pygal version of scatter-basic.

File: plots/scatter-basic/implementations/python/pygal.py

Parent Issue: #611

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🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

Light render (plot-light.png): Warm off-white background consistent with #FAF8F1 — not pure white. Title "scatter-basic · pygal · anyplot.ai" centered at top in dark ink, clearly readable. X-axis label "Study Hours per Week (hrs)" and Y-axis label "Exam Score (%)" both visible in dark secondary text. Tick labels (1.0–14.0 hrs; 20%–100%) rendered in dark text against the light background — all legible. Subtle grid lines on both axes. Two data series: teal/green (#009E73, "Passing ≥ 70%") dots clustered in the upper-right, and orange (#D55E00, "Below 70%") dots clustered in the lower-left, with a clear positive correlation arc across 180 points. Bottom legend shows both series labels clearly. All text is readable against the light background — no light-on-light failures.

Dark render (plot-dark.png): Near-black background consistent with #1A1A17 — not pure black. Title and axis labels rendered in light/off-white text, clearly readable against the dark surface. Tick labels also appear as light text — no dark-on-dark failures observed. Subtle grid lines visible as slightly lighter lines on the dark background. Data colors are identical to the light render — same teal (#009E73) and orange (#D55E00) dots in the same positions, confirming Okabe-Ito positions 1–2 are theme-independent. Bottom legend readable. All text is readable against the dark background — no dark-on-dark failures.

Both renders pass the theme-readability check.

Score: 86/100

Category	Score	Max
Visual Quality	28	30
Design Excellence	12	20
Spec Compliance	15	15
Data Quality	14	15
Code Quality	10	10
Library Mastery	7	10
Total	86	100

Visual Quality (28/30)

• VQ-01: Text Legibility (7/8) — All text readable in both themes; font sizes (52px title, 40px label) are above the 28px/22px pixel-based guideline but renders look proportionate at 4800×2700
• VQ-02: No Overlap (5/6) — Some point crowding in the dense lower-left region; opacity=0.7 and 70% transparency help, but dots_size=17 amplifies collision at the highest density
• VQ-03: Element Visibility (6/6) — Both series clearly visible with good marker size and Okabe-Ito green/orange contrast
• VQ-04: Color Accessibility (2/2) — Okabe-Ito palette is CVD-safe; green/orange provide adequate contrast
• VQ-05: Layout & Canvas (4/4) — 4800×2700 landscape, generous margins (margin=60), legend at bottom does not obstruct data
• VQ-06: Axis Labels & Title (2/2) — Labels include units ("hrs", "%")
• VQ-07: Palette Compliance (2/2) — First series #009E73, second #D55E00; light #FAF8F1 and dark #1A1A17 backgrounds; data colors identical across themes

Design Excellence (12/20)

• DE-01: Aesthetic Sophistication (5/8) — Intentional data split at 70% passing threshold adds narrative hierarchy; correct palette; above generic defaults
• DE-02: Visual Refinement (3/6) — Grid appropriate for scatter, clean font family throughout, bottom legend placement — limited refinement options within pygal's API
• DE-03: Data Storytelling (4/6) — Pass/fail split at the 70% threshold creates a clear focal point and communicates the study-hours-to-outcome narrative effectively

Spec Compliance (15/15)

• SC-01: Plot Type (5/5) — pygal.XY() with stroke=False is the correct scatter plot type
• SC-02: Required Features (4/4) — Transparency (opacity=0.7), descriptive axis labels, title, and grid lines all present as specified
• SC-03: Data Mapping (3/3) — Study hours on X (independent), exam scores on Y (dependent), 180 points within recommended 50–500 range, clear positive correlation
• SC-04: Title & Legend (3/3) — Title is "scatter-basic · pygal · anyplot.ai"; legend labels "Passing (≥ 70%)" and "Below 70%" match data series

Data Quality (14/15)

• DQ-01: Feature Coverage (5/6) — Strong coverage of scatter fundamentals; two-series split adds an analytical dimension; no regression line or annotation layer for additional depth
• DQ-02: Realistic Context (5/5) — Study hours vs exam scores is a classic, neutral, real-world educational scenario with plausible values
• DQ-03: Appropriate Scale (4/4) — 1–14 hours and 20–100% are realistic; 180 data points is well within the recommended range

Code Quality (10/10)

• CQ-01: KISS Structure (3/3) — Linear script, no functions or classes
• CQ-02: Reproducibility (2/2) — np.random.seed(42) ensures deterministic output
• CQ-03: Clean Imports (2/2) — All imports used; sys is needed for the path manipulation workaround
• CQ-04: Code Elegance (2/2) — Clean structure; sys.path.pop(0) workaround is necessary and explained; noqa comments justified by intentional import ordering
• CQ-05: Output & API (1/1) — Saves plot-{THEME}.png and plot-{THEME}.html correctly

Library Mastery (7/10)

• LM-01: Idiomatic Usage (4/5) — Correct pygal.XY() for scatter, Style object for full theme control, xrange/range for axis bounds, lambda formatters for custom tick display
• LM-02: Distinctive Features (3/5) — Interactive HTML output (pygal's primary distinguishing feature), opacity_hover for hover state, js=[] for offline/CDN-free output, value_formatter for tooltip customization

Score Caps Applied

• None applied

Strengths

• Excellent data storytelling: splitting at the 70% passing threshold creates a meaningful visual narrative guiding the viewer through the correlation
• Perfect Okabe-Ito palette compliance — brand green as first series, identical data colors in both themes
• Both light and dark themes render cleanly with correct backgrounds and fully readable text in both
• Clean, minimal code with deterministic seed; interactive HTML correctly generated alongside PNG
• Axis labels carry units and the study-hours/exam-scores domain is realistic, neutral, and appropriate

Weaknesses

• INK_MUTED for dark theme is #6E6D66 — deviates from the style guide value #A8A79F; the value is close to the dark background, potentially making grid lines/subtle text less visible than intended
• Font sizes (52px title, 40px labels) exceed the pixel-based library guideline of 28px/22px — renders look acceptable but are outside spec
• Minor point crowding in the low-study-hours/below-70% region; larger dots_size=17 amplifies overlap in the densest area

Issues Found

1. INK_MUTED dark theme value: #6E6D66 is darker than the #A8A79F value in the style guide, which risks subtle text/grid lines being too close to the #1A1A17 background
   • Fix: Use INK_MUTED = "#6B6A63" if THEME == "light" else "#A8A79F" per the default style guide
2. Font sizes above guideline: title_font_size=52 vs recommended 28px for pixel-based libraries
   • Fix: Reduce title to 28–34px range; axis labels to 22–26px range

AI Feedback for Next Attempt

Implementation is solid — data storytelling and palette compliance are strong. Two fixes recommended: (1) correct INK_MUTED dark theme value to #A8A79F as per the style guide; (2) bring font sizes closer to the pixel-based guidelines (title ~28–34px, labels ~22–26px). Both are minor correctness issues; the overall design and structure are approved.

Verdict: APPROVED