feat(plotnine): implement smith-chart-basic

[github-actions]

Implementation: smith-chart-basic - plotnine

Implements the plotnine version of smith-chart-basic.

File: plots/smith-chart-basic/implementations/plotnine.py

Parent Issue: #3792

---

🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

The plot displays a Smith chart with the correct circular layout. The outer boundary is a black circle representing |gamma|=1 (total reflection). Inside, light gray constant resistance circles are drawn (centered along the horizontal axis) and constant reactance arcs curve from the right edge. A horizontal real axis line passes through the center. The impedance locus is drawn as a connected blue (#306998) path with small markers showing an antenna S11 measurement sweep from 1-6 GHz. Five frequency labels (1.0 GHz, 2.2 GHz, 3.4 GHz, 4.7 GHz, 6.0 GHz) appear in yellow/gold text positioned above their corresponding data points. A red dot marks the center point (Z=Z₀) with a red label. The chart uses a clean white background with no axis labels or tick marks (appropriate for a Smith chart). The title "smith-chart-basic · plotnine · pyplots.ai" appears centered at the top in bold black text.

Quality Score: 90/100

Criteria Checklist

Visual Quality (36/40 pts)

• VQ-01: Text Legibility (9/10) - Title is large and bold, frequency labels are readable though could be slightly larger
• VQ-02: No Overlap (8/8) - No overlapping text elements
• VQ-03: Element Visibility (7/8) - Grid lines visible with appropriate alpha, data points could be slightly larger
• VQ-04: Color Accessibility (5/5) - Blue/yellow/red color scheme is colorblind-safe with good contrast
• VQ-05: Layout Balance (5/5) - Chart is well-centered with balanced margins, uses square 1:1 aspect ratio appropriately
• VQ-06: Axis Labels (0/2) - N/A for Smith chart (no conventional axes), but spec-appropriate
• VQ-07: Grid & Legend (2/2) - Grid lines are subtle with appropriate alpha, no legend needed

Spec Compliance (24/25 pts)

• SC-01: Plot Type (8/8) - Correct Smith chart with resistance circles and reactance arcs
• SC-02: Data Mapping (5/5) - Complex impedance correctly converted to reflection coefficient (gamma) coordinates
• SC-03: Required Features (5/5) - All required features present: grid, normalized impedance, connected locus curve, frequency labels, center marker
• SC-04: Data Range (3/3) - All data visible within unit circle boundary
• SC-05: Legend Accuracy (1/2) - No legend needed, but labels could better explain the grid values
• SC-06: Title Format (2/2) - Correct format: "smith-chart-basic · plotnine · pyplots.ai"

Data Quality (18/20 pts)

• DQ-01: Feature Coverage (7/8) - Shows impedance variation with frequency creating realistic spiral pattern, visits different regions of Smith chart
• DQ-02: Realistic Context (7/7) - Antenna S11 measurement from 1-6 GHz is a realistic RF engineering scenario
• DQ-03: Appropriate Scale (4/5) - Impedance values around 50 ohms reference are realistic, frequency range is typical for antenna design

Code Quality (9/10 pts)

• CQ-01: KISS Structure (3/3) - Flat structure: imports → data generation → plot construction → save
• CQ-02: Reproducibility (3/3) - Uses np.random.seed(42)
• CQ-03: Clean Imports (2/2) - All imports are used
• CQ-04: No Deprecated API (1/1) - Uses current plotnine API
• CQ-05: Output Correct (0/1) - Saves as "plot.png" correctly (1/1)

Library Features (3/5 pts)

• LF-01: Uses plotnine grammar of graphics with layered geom_path and geom_point, coord_fixed for aspect ratio, proper theming

Strengths

• Excellent implementation of Smith chart using plotnine's grammar of graphics approach
• Mathematically correct calculation of constant resistance circles and reactance arcs
• Proper conversion from complex impedance to reflection coefficient coordinates
• Clean layered composition with grid, boundary, axis, data locus, and annotations
• Realistic RF engineering data scenario with antenna S11 measurements
• Good use of coord_fixed for maintaining circular aspect ratio

Weaknesses

• Frequency labels in yellow (#FFD43B) may have lower contrast against white background than ideal
• Grid line labels (r=0, r=0.2, x=0.5, etc.) not shown - would enhance educational value
• Data point markers could be slightly larger for better visibility at full resolution

Verdict: APPROVED