feat(plotnine): implement smith-chart-basic

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

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+""" pyplots.ai
+smith-chart-basic: Smith Chart for RF/Impedance
+Library: plotnine 0.15.2 | Python 3.13.11
+Quality: 90/100 | Created: 2026-01-15
+"""
+
+import numpy as np
+import pandas as pd
+from plotnine import (
+    aes,
+    annotate,
+    coord_fixed,
+    element_blank,
+    element_rect,
+    element_text,
+    geom_path,
+    geom_point,
+    geom_text,
+    ggplot,
+    labs,
+    scale_x_continuous,
+    scale_y_continuous,
+    theme,
+)
+
+
+# Reference impedance
+Z0 = 50
+
+# Generate Smith chart grid - constant resistance circles
+# For resistance r, circle center at (r/(r+1), 0) with radius 1/(r+1)
+r_values = [0, 0.2, 0.5, 1, 2, 5]
+theta = np.linspace(0, 2 * np.pi, 200)
+
+r_circle_data = []
+for r in r_values:
+    cx = r / (r + 1)
+    radius = 1 / (r + 1)
+    x = cx + radius * np.cos(theta)
+    y = radius * np.sin(theta)
+    # Clip to unit circle
+    mask = x**2 + y**2 <= 1.001
+    r_circle_data.append(pd.DataFrame({"x": x[mask], "y": y[mask], "type": "r_circle", "value": f"r={r}"}))
+
+r_circles_df = pd.concat(r_circle_data, ignore_index=True)
+
+# Constant reactance arcs
+# For reactance x, circle center at (1, 1/x) with radius 1/|x|
+x_values = [0.2, 0.5, 1, 2, 5]
+reactance_data = []
+
+for xv in x_values:
+    # Positive reactance (upper half)
+    radius_x = 1 / abs(xv)
+    cy_pos = 1 / xv
+    t = np.linspace(0, 2 * np.pi, 500)
+    arc_x = 1 + radius_x * np.cos(t)
+    arc_y = cy_pos + radius_x * np.sin(t)
+    # Keep only points inside unit circle
+    mask = (arc_x**2 + arc_y**2 <= 1.001) & (arc_x >= -0.01)
+    if np.any(mask):
+        reactance_data.append(pd.DataFrame({"x": arc_x[mask], "y": arc_y[mask], "type": "x_arc", "value": f"x={xv}"}))
+
+    # Negative reactance (lower half)
+    cy_neg = -1 / xv
+    arc_y_neg = cy_neg + radius_x * np.sin(t)
+    mask_neg = (arc_x**2 + arc_y_neg**2 <= 1.001) & (arc_x >= -0.01)
+    if np.any(mask_neg):
+        reactance_data.append(
+            pd.DataFrame({"x": arc_x[mask_neg], "y": arc_y_neg[mask_neg], "type": "x_arc", "value": f"x=-{xv}"})
+        )
+
+reactance_df = pd.concat(reactance_data, ignore_index=True)
+
+# Outer boundary circle (|gamma| = 1)
+boundary_theta = np.linspace(0, 2 * np.pi, 200)
+boundary_df = pd.DataFrame(
+    {"x": np.cos(boundary_theta), "y": np.sin(boundary_theta), "type": "boundary", "value": "boundary"}
+)
+
+# Horizontal axis (real axis)
+axis_df = pd.DataFrame({"x": [-1, 1], "y": [0, 0], "type": "axis", "value": "axis"})
+
+# Example impedance data: antenna S11 measurement from 1-6 GHz
+np.random.seed(42)
+n_points = 50
+freq_ghz = np.linspace(1, 6, n_points)
+
+# Simulate antenna impedance variation with frequency
+# Creates realistic spiral pattern on Smith chart
+z_real = 50 + 30 * np.sin(2 * np.pi * freq_ghz / 2.5) + np.random.randn(n_points) * 3
+z_imag = 20 * np.cos(2 * np.pi * freq_ghz / 3) + 15 * (freq_ghz - 3) + np.random.randn(n_points) * 2
+
+# Normalize impedance
+z_norm = (z_real + 1j * z_imag) / Z0
+
+# Convert to reflection coefficient (gamma) for Smith chart coordinates
+gamma = (z_norm - 1) / (z_norm + 1)
+gamma_real = np.real(gamma)
+gamma_imag = np.imag(gamma)
+
+impedance_df = pd.DataFrame({"x": gamma_real, "y": gamma_imag, "freq": freq_ghz, "type": "impedance"})
+
+# Select frequency labels at key points
+label_indices = [0, 12, 24, 36, 49]
+labels_df = impedance_df.iloc[label_indices].copy()
+labels_df["label"] = [f"{f:.1f} GHz" for f in labels_df["freq"]]
+labels_df["y_offset"] = labels_df["y"] + 0.08
+
+# Combine grid data
+grid_df = pd.concat([r_circles_df, reactance_df, boundary_df, axis_df], ignore_index=True)
+
+# Create plot
+plot = (
+    ggplot()
+    # Grid lines
+    + geom_path(
+        aes(x="x", y="y", group="value"),
+        data=grid_df[grid_df["type"] == "r_circle"],
+        color="#CCCCCC",
+        size=0.5,
+        alpha=0.8,
+    )
+    + geom_path(
+        aes(x="x", y="y", group="value"), data=grid_df[grid_df["type"] == "x_arc"], color="#CCCCCC", size=0.5, alpha=0.8
+    )
+    # Boundary circle
+    + geom_path(aes(x="x", y="y"), data=boundary_df, color="#333333", size=1)
+    # Real axis
+    + geom_path(aes(x="x", y="y"), data=axis_df, color="#333333", size=0.5)
+    # Impedance locus curve
+    + geom_path(aes(x="x", y="y"), data=impedance_df, color="#306998", size=1.5)
+    # Data points
+    + geom_point(aes(x="x", y="y"), data=impedance_df, color="#306998", size=2, alpha=0.7)
+    # Frequency labels
+    + geom_text(aes(x="x", y="y_offset", label="label"), data=labels_df, color="#FFD43B", size=12, fontweight="bold")
+    # Center point marker (Z = Z0)
+    + annotate("point", x=0, y=0, color="#E74C3C", size=4)
+    + annotate("text", x=0.12, y=-0.08, label="Z=Z₀", color="#E74C3C", size=11)
+    # Styling
+    + coord_fixed(ratio=1, xlim=(-1.3, 1.3), ylim=(-1.3, 1.3))
+    + scale_x_continuous(breaks=[])
+    + scale_y_continuous(breaks=[])
+    + labs(title="smith-chart-basic · plotnine · pyplots.ai", x="", y="")
+    + theme(
+        figure_size=(12, 12),
+        plot_title=element_text(size=24, ha="center", weight="bold"),
+        panel_background=element_rect(fill="white"),
+        panel_grid_major=element_blank(),
+        panel_grid_minor=element_blank(),
+        axis_text=element_blank(),
+        axis_ticks=element_blank(),
+        plot_background=element_rect(fill="white"),
+    )
+)
+
+# Save
+plot.save("plot.png", dpi=300)

plots/smith-chart-basic/metadata/plotnine.yaml

@@ -0,0 +1,218 @@
+library: plotnine
+specification_id: smith-chart-basic
+created: '2026-01-15T21:51:40Z'
+updated: '2026-01-15T21:54:21Z'
+generated_by: claude-opus-4-5-20251101
+workflow_run: 21047489075
+issue: 3792
+python_version: 3.13.11
+library_version: 0.15.2
+preview_url: https://storage.googleapis.com/pyplots-images/plots/smith-chart-basic/plotnine/plot.png
+preview_thumb: https://storage.googleapis.com/pyplots-images/plots/smith-chart-basic/plotnine/plot_thumb.png
+preview_html: null
+quality_score: 90
+review:
+  strengths:
+  - Excellent implementation of Smith chart using plotnine 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 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
+  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.
+  criteria_checklist:
+    visual_quality:
+      score: 36
+      max: 40
+      items:
+      - id: VQ-01
+        name: Text Legibility
+        score: 9
+        max: 10
+        passed: true
+        comment: Title is large and bold, frequency labels are readable though could
+          be slightly larger
+      - id: VQ-02
+        name: No Overlap
+        score: 8
+        max: 8
+        passed: true
+        comment: No overlapping text elements
+      - id: VQ-03
+        name: Element Visibility
+        score: 7
+        max: 8
+        passed: true
+        comment: Grid lines visible with appropriate alpha, data points could be slightly
+          larger
+      - id: VQ-04
+        name: Color Accessibility
+        score: 5
+        max: 5
+        passed: true
+        comment: Blue/yellow/red color scheme is colorblind-safe with good contrast
+      - id: VQ-05
+        name: Layout Balance
+        score: 5
+        max: 5
+        passed: true
+        comment: Chart is well-centered with balanced margins, uses square 1:1 aspect
+          ratio appropriately
+      - id: VQ-06
+        name: Axis Labels
+        score: 0
+        max: 2
+        passed: true
+        comment: N/A for Smith chart (no conventional axes), but spec-appropriate
+      - id: VQ-07
+        name: Grid & Legend
+        score: 2
+        max: 2
+        passed: true
+        comment: Grid lines are subtle with appropriate alpha, no legend needed
+    spec_compliance:
+      score: 24
+      max: 25
+      items:
+      - id: SC-01
+        name: Plot Type
+        score: 8
+        max: 8
+        passed: true
+        comment: Correct Smith chart with resistance circles and reactance arcs
+      - id: SC-02
+        name: Data Mapping
+        score: 5
+        max: 5
+        passed: true
+        comment: Complex impedance correctly converted to reflection coefficient (gamma)
+          coordinates
+      - id: SC-03
+        name: Required Features
+        score: 5
+        max: 5
+        passed: true
+        comment: 'All required features present: grid, normalized impedance, connected
+          locus curve, frequency labels, center marker'
+      - id: SC-04
+        name: Data Range
+        score: 3
+        max: 3
+        passed: true
+        comment: All data visible within unit circle boundary
+      - id: SC-05
+        name: Legend Accuracy
+        score: 1
+        max: 2
+        passed: true
+        comment: No legend needed, but labels could better explain the grid values
+      - id: SC-06
+        name: Title Format
+        score: 2
+        max: 2
+        passed: true
+        comment: 'Correct format: smith-chart-basic · plotnine · pyplots.ai'
+    data_quality:
+      score: 18
+      max: 20
+      items:
+      - id: DQ-01
+        name: Feature Coverage
+        score: 7
+        max: 8
+        passed: true
+        comment: Shows impedance variation with frequency creating realistic spiral
+          pattern, visits different regions of Smith chart
+      - id: DQ-02
+        name: Realistic Context
+        score: 7
+        max: 7
+        passed: true
+        comment: Antenna S11 measurement from 1-6 GHz is a realistic RF engineering
+          scenario
+      - id: DQ-03
+        name: Appropriate Scale
+        score: 4
+        max: 5
+        passed: true
+        comment: Impedance values around 50 ohms reference are realistic, frequency
+          range is typical for antenna design
+    code_quality:
+      score: 9
+      max: 10
+      items:
+      - id: CQ-01
+        name: KISS Structure
+        score: 3
+        max: 3
+        passed: true
+        comment: 'Flat structure: imports, data generation, plot construction, save'
+      - id: CQ-02
+        name: Reproducibility
+        score: 3
+        max: 3
+        passed: true
+        comment: Uses np.random.seed(42)
+      - id: CQ-03
+        name: Clean Imports
+        score: 2
+        max: 2
+        passed: true
+        comment: All imports are used
+      - id: CQ-04
+        name: No Deprecated API
+        score: 1
+        max: 1
+        passed: true
+        comment: Uses current plotnine API
+      - id: CQ-05
+        name: Output Correct
+        score: 0
+        max: 1
+        passed: false
+        comment: 'Minor: could use higher dpi for 4800x2700 target'
+    library_features:
+      score: 3
+      max: 5
+      items:
+      - id: LF-01
+        name: Distinctive Features
+        score: 3
+        max: 5
+        passed: true
+        comment: Uses plotnine grammar of graphics with layered geom_path and geom_point,
+          coord_fixed for aspect ratio, proper theming
+  verdict: APPROVED
+impl_tags:
+  dependencies: []
+  techniques:
+  - annotations
+  - layer-composition
+  - patches
+  patterns:
+  - data-generation
+  - iteration-over-groups
+  - matrix-construction
+  dataprep:
+  - normalization
+  styling:
+  - minimal-chrome
+  - alpha-blending