feat(matplotlib): implement gauge-basic

[github-actions]

Implementation: gauge-basic - python/matplotlib

Implements the python/matplotlib version of gauge-basic.

File: plots/gauge-basic/implementations/python/matplotlib.py

Parent Issue: #857

---

🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

Light render (plot-light.png): The gauge renders on a warm off-white #FAF8F1 background with a clean semi-circular dial. Three color zones span the arc: vermillion (#D55E00) for bad (0–30), orange-gold (#E69F00) for warning (30–70), and teal green (#009E73) for good (70–100). Major tick marks at 0, 25, 50, 75, 100 are labeled in bold dark text (fontsize 18) with clear readability. A thin black needle points precisely to the 72 mark in the good zone. A two-tone center cap (dark outer, light inner) anchors the needle cleanly. The value "72" is displayed prominently in brand green (fontsize 56) below the dial, with "Current Sales" in muted INK_MUTED tone below it. The title "gauge-basic · matplotlib · anyplot.ai" appears in dark text at the top. All text is clearly readable against the light background.

Dark render (plot-dark.png): The same gauge renders on a warm near-black #1A1A17 background. The three zone colors are identical to the light render (vermillion, orange-gold, teal green — Okabe-Ito positions correctly unchanged). The needle is now rendered in #F0EFE8 (INK token in dark mode), making it cleanly visible against the dark background. Tick labels and major labels render in light-gray #B8B7B0 (INK_SOFT), fully readable. The title appears in #F0EFE8 light text, clearly legible. The value "72" remains in #009E73 brand green, which is highly readable on the dark surface. "Current Sales" shows in muted #A8A79F. No dark-on-dark issues — all text elements use proper theme-adaptive INK tokens. Both renders pass the legibility check.

Score: 91/100

Category	Score	Max
Visual Quality	29	30
Design Excellence	15	20
Spec Compliance	15	15
Data Quality	15	15
Code Quality	10	10
Library Mastery	7	10
Total	91	100

Visual Quality (29/30)

• VQ-01: Text Legibility (8/8) — All sizes explicitly set: title 24pt, tick labels 18pt, value 56pt, subtitle 20pt. Readable in both themes.
• VQ-02: No Overlap (6/6) — Tick labels are evenly spaced around the semi-circle with no collisions.
• VQ-03: Element Visibility (6/6) — Zone wedges, needle, center cap, and all labels are clearly visible.
• VQ-04: Color Accessibility (2/2) — CVD-safe Okabe-Ito zone colors; needle contrasts with all zones in both themes.
• VQ-05: Layout & Canvas (3/4) — Well-proportioned; minor empty space on left/right edges is inherent to semi-circular gauge in landscape format.
• VQ-06: Axis Labels & Title (2/2) — Title matches required format; "Current Sales" + "72" provide clear contextual labels.
• VQ-07: Palette Compliance (2/2) — Brand green #009E73 used for the "good" zone and value label; all Okabe-Ito zone colors; backgrounds #FAF8F1/#1A1A17 correct; all chrome tokens theme-adaptive.

Design Excellence (15/20)

• DE-01: Aesthetic Sophistication (6/8) — Clearly above defaults: intentional Okabe-Ito zone colors, two-tone center cap, custom tick rendering. Not yet at publication-ready level.
• DE-02: Visual Refinement (5/6) — Excellent polish: ax.axis("off"), wedge edges match PAGE_BG for clean zone separation, inner cutout for professional dial look, generous whitespace.
• DE-03: Data Storytelling (4/6) — Clear visual hierarchy: zones (background layer) → needle (indicator) → large green "72" (focal point). Message is immediately clear — value is in the "good" zone.

Spec Compliance (15/15)

• SC-01: Plot Type (5/5) — Correct semi-circular gauge with needle and color zones.
• SC-02: Required Features (4/4) — Color zones (red/yellow/green), prominent value display, needle, thresholds at [30, 70].
• SC-03: Data Mapping (3/3) — value=72, min=0, max=100; needle correctly positioned in the good zone.
• SC-04: Title & Legend (3/3) — Title "gauge-basic · matplotlib · anyplot.ai" correct; no legend needed (zones are self-explanatory).

Data Quality (15/15)

• DQ-01: Feature Coverage (6/6) — Shows all gauge aspects: color zones, scale ticks, needle indicator, numerical value, and context label.
• DQ-02: Realistic Context (5/5) — "Current Sales = 72" on 0–100 scale is a neutral, real-world business KPI scenario.
• DQ-03: Appropriate Scale (4/4) — 0–100 range is standard for percentage/score-based gauges; value 72 sits meaningfully past the warning threshold.

Code Quality (10/10)

• CQ-01: KISS Structure (3/3) — Linear script: imports → theme tokens → data → geometry → plot → save. No functions or classes.
• CQ-02: Reproducibility (2/2) — All data hardcoded; fully deterministic.
• CQ-03: Clean Imports (2/2) — All four imports (os, mpatches, plt, np) are actively used.
• CQ-04: Code Elegance (2/2) — Clean, readable Python; appropriate complexity for a custom gauge; well-named variables.
• CQ-05: Output & API (1/1) — Saves as plot-{THEME}.png with correct DPI and facecolor.

Library Mastery (7/10)

• LM-01: Idiomatic Usage (4/5) — Proper fig/ax pattern, ax.add_patch() for geometry, correct Axes-method approach throughout.
• LM-02: Distinctive Features (3/5) — Uses mpatches.Wedge for arcs, plt.Circle for center cap, and ax.plot for custom tick marks — distinctively matplotlib approaches to building a gauge from primitives.

Score Caps Applied

• None applied.

Strengths

• Perfect theme adaptation: needle, tick labels, and center cap all flip correctly between light and dark using INK tokens.
• Okabe-Ito zone colors are semantically matched (brand green = good, vermillion = bad) and match the palette exactly.
• Strong visual storytelling: the large green "72" focal point combined with the needle in the green zone creates an immediately readable message.
• Excellent code quality: linear KISS structure, no randomness needed, all imports used.
• Full spec compliance with all required features (zones, needle, thresholds, prominent value display).

Weaknesses

• Minor canvas utilization: the landscape 16:9 format leaves some empty space on the sides of the semi-circle; a square canvas could improve proportions.
• DE-01 could reach 8/8 with more typographic refinement (e.g., a subtle arc annotation showing zone labels like "Poor / Fair / Good" rather than relying solely on color intuition).

Issues Found

None significant. The 1-point VQ-05 deduction is inherent to the gauge chart geometry in landscape format.

AI Feedback for Next Attempt

Implementation is strong. If regenerating: consider using a square canvas (12×12) to better utilize space around the semi-circle, and optionally add subtle zone labels ("Poor", "Fair", "Good") as text inside or beneath the arcs to reduce reliance on color-only encoding. These are enhancements, not corrections.

Verdict: APPROVED