feat(letsplot): implement scatter-basic

[github-actions]

Implementation: scatter-basic - python/letsplot

Implements the python/letsplot version of scatter-basic.

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

Parent Issue: #611

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🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

Light render (plot-light.png): Scatter plot on warm off-white #FAF8F1 background. 180 brand-green (#009E73) circles with subtle background-colored stroke, showing study hours (1–10) vs exam scores (30–105 points). Title "scatter-basic · letsplot · anyplot.ai" in bold dark text top-left; axis labels "Study Hours per Day" and "Exam Score (points)" in dark INK; tick labels in softer INK_SOFT. Subtle grid lines only on major divisions. Clear positive correlation pattern visible across the full data range. All text is readable against the warm off-white background — no legibility issues. Legibility: PASS.

Dark render (plot-dark.png): Same layout on warm near-black #1A1A17 background. Data points remain identical #009E73 green — palette is theme-invariant as required. Title, axis labels, and tick labels flip to light colors (#F0EFE8 and #B8B7B0) — clearly readable. Grid lines are very subtle but visible against the dark surface. No dark-on-dark failures detected; brand green #009E73 stands out well against near-black. Legibility: PASS.

Both paragraphs are required. A review that only describes one render is invalid.

Score: 89/100

Category	Score	Max
Visual Quality	30	30
Design Excellence	11	20
Spec Compliance	15	15
Data Quality	15	15
Code Quality	10	10
Library Mastery	8	10
Total	89	100

Visual Quality (30/30)

• VQ-01: Text Legibility (8/8) — All sizes explicitly set: title=24pt, axis=20pt, ticks=16pt
• VQ-02: No Overlap (6/6) — No element overlap in either render
• VQ-03: Element Visibility (6/6) — 180 points, size=6, alpha=0.75, shape=21 with PAGE_BG stroke; well-adapted
• VQ-04: Color Accessibility (2/2) — Single series #009E73, CVD-safe
• VQ-05: Layout & Canvas (4/4) — Plot fills canvas well with balanced margins
• VQ-06: Axis Labels & Title (2/2) — Descriptive with units: "Study Hours per Day", "Exam Score (points)"
• VQ-07: Palette Compliance (2/2) — Brand green #009E73 as sole data color; backgrounds #FAF8F1 / #1A1A17; theme-correct chrome in both renders

Design Excellence (11/20)

• DE-01: Aesthetic Sophistication (5/8) — Above defaults: theme-adaptive stroke (shape=21 + PAGE_BG color), warm backgrounds, pre-blended GRID color. Polished but not yet "strong design"
• DE-02: Visual Refinement (4/6) — Minor grid removed, axis ticks removed, subtle major grid only — good refinement beyond library defaults
• DE-03: Data Storytelling (2/6) — Correlation pattern is visible but no visual hierarchy or emphasis; no trend line or focal point to guide the viewer

Spec Compliance (15/15)

• SC-01: Plot Type (5/5) — Correct scatter plot
• SC-02: Required Features (4/4) — Transparency, axis labels, descriptive title, grid — all present
• SC-03: Data Mapping (3/3) — X=independent (study hours), Y=dependent (exam scores), r~0.7 with noise
• SC-04: Title & Legend (3/3) — "scatter-basic · letsplot · anyplot.ai" exact format; no legend (single series — appropriate)

Data Quality (15/15)

• DQ-01: Feature Coverage (6/6) — Full scatter characteristics: spread, correlation, natural variation
• DQ-02: Realistic Context (5/5) — Study hours vs exam scores: real, neutral, educational domain
• DQ-03: Appropriate Scale (4/4) — 1–10 hours/day realistic; 30–105 score range labeled as "points"

Code Quality (10/10)

• CQ-01: KISS Structure (3/3) — Imports → data → plot → save; no functions or classes
• CQ-02: Reproducibility (2/2) — np.random.seed(42)
• CQ-03: Clean Imports (2/2) — All imported symbols are used
• CQ-04: Code Elegance (2/2) — Clean, Pythonic, appropriate complexity
• CQ-05: Output & API (1/1) — plot-{THEME}.png + plot-{THEME}.html with scale=3

Library Mastery (8/10)

• LM-01: Idiomatic Usage (5/5) — Expert ggplot2 grammar: ggplot + geom_point + labs + theme, ggsize(), ggsave(scale=3) — all idiomatic
• LM-02: Distinctive Features (3/5) — shape=21 fill/stroke paradigm and dual HTML+PNG export are lets-plot-native; however no geom_smooth() or other truly distinctive lets-plot capability is used

Score Caps Applied

• None — DE-01=5 > 2 so the "correct but boring" cap does not apply

Strengths

• Theme-adaptive chrome is fully correct in both renders: PAGE_BG, INK, INK_SOFT tokens applied to all non-data elements
• Pre-blended GRID color avoids lets-plot element_line alpha limitation — thoughtful workaround
• shape=21 with PAGE_BG stroke creates subtle theme-adaptive marker definition
• All font sizes explicitly set meeting DPI-based requirements (24/20/16 pt)
• Perfect spec compliance: seed, axis labels with units, correct title format, HTML+PNG output

Weaknesses

• DE-03 LOW: No visual hierarchy or emphasis; adding geom_smooth() (a natural lets-plot feature) would create a focal point and communicate the correlation insight
• DE-01 MODERATE: Design is above defaults but not "strong design" — a subtle trend line and/or a subtitle noting the relationship would push this to strong design
• LM-02 LOW: Generic ggplot2-style usage only; geom_smooth() or lets-plot's native geom_density2d() overlay would demonstrate lets-plot's distinctive capabilities

Issues Found

1. DE-03 LOW: Data displayed but viewer must find the story themselves
   • Fix: Add geom_smooth(method="lm", color=INK_SOFT, fill=INK_SOFT, alpha=0.15, size=1.0) to show the trend line — this naturally doubles as a lets-plot distinctive feature
2. LM-02 LOW: No lets-plot-distinctive features beyond shape=21
   • Fix: geom_smooth() resolves both DE-03 and LM-02 simultaneously

AI Feedback for Next Attempt

Add a geom_smooth(method="lm", color=INK_SOFT, fill=INK_SOFT, alpha=0.15, size=1.0) trend line layer. This single change: (1) creates visual hierarchy that guides the viewer to the correlation insight (fixes DE-03), (2) demonstrates lets-plot's built-in stat/geom system (fixes LM-02), and (3) pushes aesthetic sophistication to "strong design" level (improves DE-01). Place it before geom_point so points render on top. Keep everything else — the theme-adaptive chrome, the shape=21 stroke technique, and the data are all excellent.

Verdict: REJECTED