feat(plotnine): implement bode-basic

[github-actions]

Implementation: bode-basic - plotnine

Implements the plotnine version of bode-basic.

File: plots/bode-basic/implementations/plotnine.py

Parent Issue: #4411

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🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

The plot displays a two-panel Bode diagram for a third-order transfer function. The top panel shows Magnitude (dB) vs Frequency (Hz) on a logarithmic x-axis, with the blue response curve starting at ~14 dB and rolling off to about -175 dB. The bottom panel shows Phase (degrees) vs Frequency (Hz), with the phase starting near 0° and decreasing to approximately -270°. Dashed gray reference lines are drawn at 0 dB and -180°. Orange square markers indicate the phase crossover point, and purple circle markers indicate the gain crossover point. Annotations read "GM = 8.1 dB" in orange and "PM = 32°" in purple. The title reads "bode-basic · plotnine · pyplots.ai" centered at the top. The background is white with subtle light gray major grid lines.

Score: 85/100

Category	Score	Max
Visual Quality	27	30
Design Excellence	13	20
Spec Compliance	15	15
Data Quality	14	15
Code Quality	9	10
Library Mastery	7	10
Total	85	100

Visual Quality (27/30)

• VQ-01: Text Legibility (8/8) - All font sizes explicitly set: title 24pt, axis_title 20pt, axis_text 16pt, strip_text 20pt. All text clearly readable.
• VQ-02: No Overlap (6/6) - No overlapping text elements. Annotations are well-positioned away from lines and markers.
• VQ-03: Element Visibility (4/6) - Main response curves are clearly visible. However, the gain margin and phase margin vertical segments are barely distinguishable — they appear as very short lines near the markers and don't stand out as clear margin indicators.
• VQ-04: Color Accessibility (4/4) - Blue (#306998), orange (#E8833A), and purple (#9467BD) are colorblind-safe and have good contrast against the white background.
• VQ-05: Layout & Canvas (3/4) - The magnitude panel has significant unused vertical space in the lower portion (curve drops to -175 dB but the key details are all near 0 dB). The phase panel is better proportioned.
• VQ-06: Axis Labels & Title (2/2) - X-axis labeled "Frequency (Hz)" with units. Facet strips provide panel-specific y-labels with units ("Magnitude (dB)", "Phase (degrees)").

Design Excellence (13/20)

• DE-01: Aesthetic Sophistication (5/8) - Custom color palette with Python Blue, orange, and purple. Thoughtful typography hierarchy with explicit sizing. Above library defaults but not publication-level polish.
• DE-02: Visual Refinement (4/6) - theme_minimal removes spines, minor grid disabled, major grid subtly styled (#ECEFF1, 0.4), strip background has custom fill. Good refinement but not fully polished.
• DE-03: Data Storytelling (4/6) - Gain and phase margins are highlighted with color-coded annotations and distinct marker shapes (circles vs squares), creating visual hierarchy that guides the viewer to stability information. Effective for an engineering plot.

Spec Compliance (15/15)

• SC-01: Plot Type (5/5) - Correct dual-panel Bode plot with magnitude on top and phase on bottom.
• SC-02: Required Features (4/4) - All spec features present: dual-panel layout, gain margin annotation, phase margin annotation, reference lines at 0 dB and -180°, logarithmic frequency axis, grid lines.
• SC-03: Data Mapping (3/3) - X=frequency (log-spaced), Y=magnitude(dB)/phase(degrees). Correct mapping.
• SC-04: Title & Legend (3/3) - Title follows exact format "bode-basic · plotnine · pyplots.ai". No legend needed for single-series plot with color-coded annotations.

Data Quality (14/15)

• DQ-01: Feature Coverage (5/6) - Shows gain margin, phase margin, crossover frequencies, and phase rolloff. The third-order system doesn't exhibit a resonance peak, which the spec mentions as a possible feature ("showing resonance peak and phase rolloff").
• DQ-02: Realistic Context (5/5) - Third-order open-loop transfer function G(s) = 5/((s+1)(0.5s+1)(0.2s+1)) is a realistic control systems engineering example. Neutral topic.
• DQ-03: Appropriate Scale (4/4) - GM ≈ 8.1 dB and PM ≈ 32° are realistic stability margins for this type of system. Frequency range 0.01-100 Hz is appropriate.

Code Quality (9/10)

• CQ-01: KISS Structure (3/3) - Follows imports → data → plot → save structure with no functions or classes.
• CQ-02: Reproducibility (2/2) - Fully deterministic — analytical transfer function with no random components.
• CQ-03: Clean Imports (2/2) - All imports are used.
• CQ-04: Code Elegance (1/2) - Code is well-structured but somewhat verbose with many small DataFrames (gm_seg, pm_seg, gc_pt, pm_pt, pc_mag_pt, pc_phase_pt, gm_label, pm_label) needed for panel-specific annotations in plotnine's faceting system. Acceptable given plotnine constraints.
• CQ-05: Output & API (1/1) - Saves as plot.png with dpi=300.

Library Mastery (7/10)

• LM-01: Idiomatic Usage (4/5) - Good use of plotnine grammar: ggplot + aes + geom layers + facet_wrap + scale_x_log10 + theme composition. The faceting approach for dual panels is idiomatic. Could be slightly more elegant with data organization.
• LM-02: Distinctive Features (3/5) - Uses facet_wrap with scales="free_y" and pd.Categorical for panel ordering — distinctive ggplot2/plotnine features. Multiple geom layers with separate data sources demonstrate plotnine's layer composition model.

Score Caps Applied

• None

Strengths

• Full spec compliance with all required Bode plot features (dual panels, margins, reference lines, log scale)
• Effective color-coded annotation system distinguishing gain margin (orange) and phase margin (purple)
• Deterministic analytical data from a realistic third-order transfer function
• Idiomatic plotnine usage with facet_wrap for dual-panel layout
• Explicit font sizing for all text elements

Weaknesses

• Gain margin and phase margin vertical segments are barely visible — they don't clearly show the "distance" between crossover point and reference line
• Magnitude panel has excessive unused vertical space below the curve
• Many small DataFrames for annotations add verbosity (inherent to plotnine faceting but could be consolidated)

Issues Found

1. VQ-03 MEDIUM: Gain/phase margin vertical segments are barely visible as margin indicators
   • Fix: Increase segment line width, add arrowheads, or use a different visual encoding to make the margin distances more prominent
2. VQ-05 MINOR: Magnitude panel vertical space not well utilized
   • Fix: Consider limiting y-axis range on magnitude panel or adjusting panel height ratios
3. DE-01 MEDIUM: Good but not publication-level polish
   • Fix: Consider adding subtle color fills or shading for the margin regions, refine marker styling
4. DQ-01 MINOR: Transfer function doesn't show resonance peak
   • Fix: Use a second-order underdamped system (e.g., with damping ratio ζ < 0.5) to show a clear resonance peak as mentioned in spec

AI Feedback for Next Attempt

Make gain/phase margin segments more visually prominent — increase line width, consider adding annotation arrows or shaded regions to clearly indicate margin distances. Consider using a second-order underdamped transfer function to show a resonance peak. Reduce unused space in magnitude panel. Consolidate annotation DataFrames where possible to reduce code verbosity.

Verdict: REJECTED

[github-actions]

🔧 Repair Attempt 1/3

Applied fixes based on AI review feedback.

Status: Repair completed, re-triggering review...

---

🤖 impl-repair

[claude]

AI Review - Attempt 2/3

Image Description

The plot displays a Bode plot with two vertically stacked panels on a light gray (#FAFAFA) background. The top panel is labeled "Magnitude (dB)" with a light blue/purple strip header and shows a blue (#306998) curve starting at ~+10 dB at 0.1 Hz, crossing 0 dB around 0.4 Hz, and declining to -70 dB at 10 Hz. A thick orange (#D35400) vertical segment marks the gain margin between the magnitude at phase crossover (-8 dB) and the 0 dB reference line, with an orange "GM = 8.1 dB" label. A purple circle marks the gain crossover point, and an orange square marks the phase crossover point on this panel. The bottom panel labeled "Phase (degrees)" shows the phase curve starting at ~-55° and declining to -260°. A thick purple (#7D3C98) vertical segment marks the phase margin between the phase at gain crossover (-148°) and the -180° reference line, with a purple "PM = 32°" label. Dashed horizontal reference lines appear at 0 dB and -180°. Dotted vertical guide lines mark both crossover frequencies across both panels. The x-axis is logarithmic labeled "Frequency (Hz)" with ticks at 0.1, 1, and 10. Title reads "bode-basic · plotnine · pyplots.ai" in dark navy bold text.

Score: 86/100

Category	Score	Max
Visual Quality	27	30
Design Excellence	13	20
Spec Compliance	15	15
Data Quality	14	15
Code Quality	10	10
Library Mastery	7	10
Total	86	100

Visual Quality (27/30)

• VQ-01: Text Legibility (7/8) — All font sizes explicitly set (title=24, axis_title=20, axis_text=16, strip_text=20). Annotation text at size=14 in geom_text is readable but slightly small relative to other elements.
• VQ-02: No Overlap (6/6) — No text collisions. Annotations positioned cleanly to the right of margin segments.
• VQ-03: Element Visibility (5/6) — Main line well-sized (size=2.2). Markers clearly visible (size=6). The gain margin segment is quite short (~8 dB span) making it less prominent than the phase margin segment.
• VQ-04: Color Accessibility (4/4) — Blue, orange, and purple are distinguishable for all forms of color vision deficiency. Good contrast against white panels.
• VQ-05: Layout & Canvas (3/4) — Square 3600×3600 format is appropriate. Panels fill canvas reasonably but the magnitude panel has significant unused vertical space (y-axis extends to -70 dB with data mostly above -40 dB in the interesting region).
• VQ-06: Axis Labels & Title (2/2) — "Frequency (Hz)" with units, strip text serves as y-axis labels with units ("Magnitude (dB)", "Phase (degrees)").

Design Excellence (13/20)

• DE-01: Aesthetic Sophistication (5/8) — Custom color palette (Python blue, orange, purple), custom text color hierarchy (#263238, #37474F, #546E7A, #1A237E), custom strip backgrounds (#E8EAF6), light page background. Above defaults but not publication-showcase level.
• DE-02: Visual Refinement (4/6) — theme_minimal removes spines, subtle major grid (color="#E0E0E0", size=0.3), minor grid removed, custom strip styling, panel spacing configured. Good refinement.
• DE-03: Data Storytelling (4/6) — Gain and phase margins are visually highlighted with colored segments and bold labels, creating clear focal points. Different marker shapes (circles vs squares) distinguish gain and phase crossover points. Viewer immediately understands stability margins.

Spec Compliance (15/15)

• SC-01: Plot Type (5/5) — Correct dual-panel Bode plot with magnitude on top, phase on bottom.
• SC-02: Required Features (4/4) — Dual-panel layout ✓, gain margin annotation ✓, phase margin annotation ✓, reference lines at 0 dB and -180° ✓, logarithmic frequency axis ✓, grid lines ✓.
• SC-03: Data Mapping (3/3) — Frequency on x-axis (log scale), magnitude in dB on top panel, phase in degrees on bottom panel. All correct.
• SC-04: Title & Legend (3/3) — Title "bode-basic · plotnine · pyplots.ai" follows required format. No legend needed for single-series with annotations.

Data Quality (14/15)

• DQ-01: Feature Coverage (5/6) — Shows third-order system with clear gain/phase margin behavior, resonance rolloff, and crossover points. Frequency range (0.1–10 Hz) captures the interesting dynamics but is narrower than what might fully showcase the flat passband and steep rolloff regions.
• DQ-02: Realistic Context (5/5) — Third-order open-loop transfer function G(s) = 5/[(s+1)(0.5s+1)(0.2s+1)] is a realistic control systems example with realistic margin values (GM=8.1 dB, PM=32°).
• DQ-03: Appropriate Scale (4/4) — Values are physically appropriate for the transfer function. Stability margins are realistic for an engineering system.

Code Quality (10/10)

• CQ-01: KISS Structure (3/3) — Linear flow: imports → data generation → DataFrame construction → plot → save. No functions or classes.
• CQ-02: Reproducibility (2/2) — Fully deterministic (analytic transfer function, no randomness).
• CQ-03: Clean Imports (2/2) — All imports are used in the implementation.
• CQ-04: Code Elegance (2/2) — Clean, well-organized. Multiple DataFrames for annotation layers is necessary for plotnine's grammar approach.
• CQ-05: Output & API (1/1) — Saves as plot.png with dpi=300 using current API.

Library Mastery (7/10)

• LM-01: Idiomatic Usage (4/5) — Good use of ggplot grammar: aes mapping, geom layers, facet_wrap with free_y for dual panels, scale_x_log10, CategoricalDtype for panel ordering. Could leverage more advanced features like scale_y_continuous with custom breaks.
• LM-02: Distinctive Features (3/5) — facet_wrap with scales="free_y" for dual-panel layout is distinctively ggplot. Long-format data with CategoricalDtype for ordered facets is idiomatic. Layer composition with multiple geom types is grammar-of-graphics style.

Score Caps Applied

• None

Strengths

• Excellent spec compliance — all required features (dual panels, margin annotations, reference lines, log axis, grid) are present and correct
• Clean, well-organized code with deterministic data from a realistic transfer function
• Good use of plotnine's grammar of graphics with facet_wrap for the dual-panel layout
• Effective color-coded annotations (orange for gain margin, purple for phase margin) with distinct marker shapes
• Thoughtful theme customization with custom text color hierarchy and subtle grid

Weaknesses

• Annotation text (geom_text size=14) is slightly small relative to axis text (size=16) — should be at least as large as axis text for key margin values
• Magnitude panel has excessive vertical range (extends to -70 dB) when the interesting region is above -20 dB, wasting canvas space
• Could use wider frequency range to show the full passband flatness and asymptotic rolloff behavior more clearly
• LM-01 could improve by using scale_y_continuous with custom formatting or breaks

Issues Found

1. VQ-01 MINOR: Annotation text size (14) is smaller than axis tick text (16), making margin labels less prominent than they should be
   • Fix: Increase geom_text size to at least 16, ideally 18 for these key annotations
2. VQ-05 MINOR: Magnitude panel y-axis extends far below the data's interesting range
   • Fix: Consider narrowing the frequency range or note that this is inherent to showing the full rolloff
3. DE-01 MODERATE: Styling is above defaults but not at publication showcase level
   • Fix: Consider adding more typographic refinement, possibly a subtitle or caption with system description
4. LM-01 MINOR: Not leveraging scale_y_continuous for custom axis formatting
   • Fix: Use scale_y_continuous with custom breaks/labels for cleaner axis ticks

AI Feedback for Next Attempt

To reach 90+: (1) Increase annotation text size to at least 16-18 to match or exceed axis text prominence — the GM and PM values are the most important information on the plot. (2) Consider using a wider frequency range (e.g., 0.01–100 Hz) to better show the flat passband and asymptotic rolloff, improving feature coverage. (3) Add more typographic polish — consider a subtitle or source caption. (4) Leverage scale_y_continuous with custom breaks for cleaner magnitude axis ticks (e.g., multiples of 20 dB). These changes would improve VQ-01 to 8, DQ-01 to 6, DE-01 to 6, and LM-01 to 5, pushing the total above 90.

Verdict: REJECTED

[github-actions]

🔧 Repair Attempt 2/3

Applied fixes based on AI review feedback.

Status: Repair completed, re-triggering review...

---

🤖 impl-repair

[claude]

AI Review - Attempt 3/3

Image Description

The plot displays a dual-panel Bode plot with "bode-basic · plotnine · pyplots.ai" as the title in dark navy bold text. The top panel is labeled "Magnitude (dB)" with a light indigo strip background, showing a blue frequency response curve starting at ~14 dB at 0.03 Hz, rolling off through 0 dB and flattening at -30 dB (clipped). The bottom panel is labeled "Phase (degrees)" with the same strip styling, showing phase rolling from ~-40° down past -250°. Both panels share a logarithmic frequency axis labeled "Frequency (Hz)" with ticks at 0.1, 1, and 10. A dashed gray reference line marks 0 dB in the magnitude panel and -180° in the phase panel. Dotted vertical guide lines mark the gain and phase crossover frequencies. An orange vertical segment shows the gain margin (~8 dB) with a bold orange "GM = 8.0 dB" label. A purple vertical segment shows the phase margin (~33°) with a bold purple "PM = 33°" label. Purple circles mark gain crossover points, orange squares mark phase crossover points. The background is light gray (#FAFAFA) with white panel interiors and subtle two-level grid lines.

Score: 89/100

Category	Score	Max
Visual Quality	29	30
Design Excellence	14	20
Spec Compliance	15	15
Data Quality	14	15
Code Quality	10	10
Library Mastery	7	10
Total	89	100

Visual Quality (29/30)

• VQ-01: Text Legibility (8/8) - All font sizes explicitly set: title 24pt, axis_title 20pt, axis_text 16pt, strip_text 20pt
• VQ-02: No Overlap (6/6) - All text and markers clearly separated and readable
• VQ-03: Element Visibility (6/6) - Line thickness 2.5, markers size 7, margin segments size 5.0 — all well-adapted
• VQ-04: Color Accessibility (4/4) - Blue/orange/purple palette is colorblind-safe with strong contrast
• VQ-05: Layout & Canvas (3/4) - Square 12×12 format works but landscape would better serve the log frequency axis; magnitude clipped at -30 dB creates a flat line at bottom
• VQ-06: Axis Labels & Title (2/2) - "Frequency (Hz)" with units; panel strips "Magnitude (dB)" and "Phase (degrees)" serve as y-labels with units

Design Excellence (14/20)

• DE-01: Aesthetic Sophistication (6/8) - Custom color palette (Python Blue main line, orange GM, purple PM), custom backgrounds (#FAFAFA plot, #E8EAF6 strips, white panels), intentional color coding, good typography hierarchy
• DE-02: Visual Refinement (4/6) - theme_minimal removes spines, subtle two-level grid (major #E0E0E0, minor #F0F0F0), custom strip and panel backgrounds, generous panel spacing — good but not every detail polished
• DE-03: Data Storytelling (4/6) - Color-coded GM/PM annotations with distinct marker shapes (circles vs squares) create clear focal points and visual hierarchy; viewer immediately sees stability margins

Spec Compliance (15/15)

• SC-01: Plot Type (5/5) - Correct dual-panel Bode plot with magnitude on top and phase on bottom
• SC-02: Required Features (4/4) - All features present: dual-panel layout, GM/PM annotations, reference lines at 0 dB and -180°, log frequency scale, grid lines
• SC-03: Data Mapping (3/3) - Frequency on log x-axis, magnitude in dB on y (top), phase in degrees on y (bottom)
• SC-04: Title & Legend (3/3) - Title "bode-basic · plotnine · pyplots.ai" correct; no legend needed for single-series with annotations

Data Quality (14/15)

• DQ-01: Feature Coverage (5/6) - Shows gain/phase rolloff, gain and phase margins, crossover frequencies with distinct markers; could show a more prominent resonance peak
• DQ-02: Realistic Context (5/5) - Third-order transfer function G(s) = 5/[(s+1)(0.5s+1)(0.2s+1)] is a realistic control systems scenario
• DQ-03: Appropriate Scale (4/4) - Frequency range 0.03–30 Hz, magnitude 14 to -30 dB, phase -40° to -270° — all realistic

Code Quality (10/10)

• CQ-01: KISS Structure (3/3) - Linear flow: imports → data → plot → save, no functions/classes
• CQ-02: Reproducibility (2/2) - Fully deterministic (transfer function computation, no randomness)
• CQ-03: Clean Imports (2/2) - All imports used
• CQ-04: Code Elegance (2/2) - Clean, well-structured; data prep for faceting is verbose but necessary for plotnine grammar
• CQ-05: Output & API (1/1) - Saves as plot.png with dpi=300

Library Mastery (7/10)

• LM-01: Idiomatic Usage (4/5) - Good use of ggplot grammar: aes, multiple geom layers, facet_wrap, scale_x_log10, theme customization
• LM-02: Distinctive Features (3/5) - facet_wrap with scales="free_y" for dual panels, CategoricalDtype for panel ordering, layer composition pattern — distinctive to grammar-of-graphics libraries

Score Caps Applied

• None

Strengths

• Full spec compliance with all required Bode plot features (dual panel, GM/PM, reference lines, log scale)
• Excellent color coding system: Python Blue for response curve, orange for gain margin, purple for phase margin
• Strong text legibility with all font sizes explicitly set
• Clean, deterministic code with realistic transfer function data
• Good use of plotnine's faceting for the dual-panel layout

Weaknesses

• Magnitude clipped at -30 dB creates an artificial flat line at the bottom of the top panel
• Square figure format (12×12) doesn't optimally serve the logarithmic frequency axis — landscape would give more horizontal room
• Design refinement good but not fully polished (DE-02: 4/6)

Issues Found

1. VQ-05 MINOR: Square figure format and magnitude clipping reduce layout score
   • Fix: Use landscape format (e.g., 16×9) and extend magnitude range or let it vary naturally
2. DE-02 MODERATE: Visual refinement is good but could be more polished
   • Fix: Further refine grid styling, consider removing minor grid, add more whitespace control

AI Feedback for Next Attempt

Strong implementation at 89/100. The main areas holding it back from 90+ are the square figure format (landscape would better serve the frequency axis) and visual refinement details. The design is already well above defaults with thoughtful color coding and typography.

Verdict: REJECTED

[github-actions]

🔧 Repair Attempt 3/3

Applied fixes based on AI review feedback.

Status: Repair completed, re-triggering review...

---

🤖 impl-repair

[claude]

AI Review - Attempt 3/3

Image Description

The plot shows a dual-panel Bode plot with the title "bode-basic · plotnine · pyplots.ai" centered at the top in dark blue bold text. The top panel is labeled "Magnitude (dB)" with a light lavender strip background, showing a blue line (#306998) starting at approximately +14 dB at low frequencies, staying relatively flat until about 0.3 Hz, then rolling off steeply to about -50 dB at the right edge. The bottom panel is labeled "Phase (degrees)" with the same strip styling, showing the phase curve starting near -30° and rolling off to approximately -270°. Reference lines are drawn as dashed light gray at 0 dB and -180°. An orange vertical segment marks the gain margin (GM = 8.0 dB) at the phase crossover frequency (~0.5 Hz) with orange square markers, and a purple vertical segment marks the phase margin (PM = 33°) at the gain crossover frequency with purple circle markers. Dotted vertical guide lines indicate crossover frequencies in both panels. The background is light gray (#FAFAFA) with white panel backgrounds and subtle grid lines. The major layout issue is that the magnitude panel occupies roughly 65% of the figure height with vast empty white space below the data, while the phase panel is extremely compressed at the bottom, making its elements crowded and hard to distinguish.

Score: 81/100

Category	Score	Max
Visual Quality	22	30
Design Excellence	14	20
Spec Compliance	14	15
Data Quality	14	15
Code Quality	10	10
Library Mastery	7	10
Total	81	100

Visual Quality (22/30)

• VQ-01: Text Legibility (7/8) — All font sizes explicitly set (title=24, axis_title=20, axis_text=16, strip=20, annotations=18). Readable throughout, minor tightness in compressed phase panel.
• VQ-02: No Overlap (4/6) — Minor crowding in the phase panel where tick labels -100 and -200 are close together and the PM annotation is near the markers. No severe overlap.
• VQ-03: Element Visibility (4/6) — Main lines clearly visible in both panels. However, the phase panel is so compressed that the PM margin segment and crossover markers are hard to distinguish from each other. The GM segment in the magnitude panel is short (~8 dB) but visible.
• VQ-04: Color Accessibility (4/4) — Excellent colorblind-safe palette: Python Blue (#306998), orange (#D35400), and purple (#7D3C98) are all clearly distinguishable under all forms of color vision deficiency.
• VQ-05: Layout & Canvas (1/4) — Severe layout imbalance. The magnitude panel occupies ~65% of the figure height but the actual data only uses the upper portion, leaving massive empty white space. The phase panel is extremely compressed at the bottom (~20% of figure height), cramming all its data, markers, and annotations into a tiny vertical band. The two faceted panels are very disproportionate.
• VQ-06: Axis Labels & Title (2/2) — "Frequency (Hz)" x-axis label with units, strip labels "Magnitude (dB)" and "Phase (degrees)" serve as effective y-axis labels with units.

Design Excellence (14/20)

• DE-01: Aesthetic Sophistication (6/8) — Custom color palette with intentional hierarchy (blue for data, orange for GM, purple for PM). Custom background (#FAFAFA), styled strip backgrounds (#E8EAF6), white panel backgrounds. Clearly above defaults with professional color choices.
• DE-02: Visual Refinement (4/6) — theme_minimal removes spines, custom grid colors (major #E0E0E0, minor #F5F5F5), subtle grid line weights, custom tick colors. Good attention to detail in theming.
• DE-03: Data Storytelling (4/6) — Annotations clearly highlight the key engineering parameters (GM and PM). Distinct marker shapes (circles for gain crossover, squares for phase crossover) and colors create visual hierarchy. Reference lines and vertical guides connect the two panels conceptually.

Spec Compliance (14/15)

• SC-01: Plot Type (5/5) — Correct dual-panel Bode plot with magnitude on top and phase on bottom, sharing logarithmic frequency axis.
• SC-02: Required Features (4/4) — All spec requirements present: gain margin annotation, phase margin annotation, reference lines at 0 dB and -180°, logarithmic frequency axis, grid lines for reading margins.
• SC-03: Data Mapping (2/3) — X-axis correctly maps log frequency, Y-axes correctly map magnitude (dB) and phase (degrees). Minor deduction because the phase panel's compressed range makes it difficult to read precise values from the plot.
• SC-04: Title & Legend (3/3) — Title format "bode-basic · plotnine · pyplots.ai" is correct. No legend needed for single-system Bode plot; margin annotations serve as effective labels.

Data Quality (14/15)

• DQ-01: Feature Coverage (5/6) — Shows a third-order transfer function with clear gain margin (8.0 dB) and phase margin (33°). Both crossover frequencies are visible. The system demonstrates the characteristic magnitude roll-off and phase lag. Minor deduction: no resonance peak shown (system has real poles only).
• DQ-02: Realistic Context (5/5) — Realistic control systems scenario: G(s) = 5/[(s+1)(0.5s+1)(0.2s+1)] is a plausible open-loop transfer function. The GM=8.0 dB and PM=33° represent a moderately stable system — realistic engineering values.
• DQ-03: Appropriate Scale (4/4) — Frequency range 0.03–30 Hz appropriate for this system. Magnitude values (+14 to -50 dB) and phase values (-30° to -270°) are physically correct for this transfer function.

Code Quality (10/10)

• CQ-01: KISS Structure (3/3) — Clean linear flow: imports → data generation → margin calculations → DataFrame construction → plot → save. No functions or classes.
• CQ-02: Reproducibility (2/2) — Fully deterministic: analytical transfer function with no random elements.
• CQ-03: Clean Imports (2/2) — All imports are used. No unused imports.
• CQ-04: Code Elegance (2/2) — Well-structured with clear comments. Data preparation for faceted plot is appropriately complex. No fake UI or over-engineering.
• CQ-05: Output & API (1/1) — Saves as plot.png with dpi=300. Uses current plotnine API.

Library Mastery (7/10)

• LM-01: Idiomatic Usage (4/5) — Good use of grammar of graphics: facet_wrap for dual panels, aes mappings, multiple geom layers composed additively, CategoricalDtype for panel ordering, scale_x_log10 for log axis.
• LM-02: Distinctive Features (3/5) — Uses facet_wrap with scales="free_y" (ggplot2-style faceting), CategoricalDtype for deterministic panel ordering, grammar of graphics layer composition with separate data frames per geom layer. These are distinctly plotnine/ggplot2 patterns.

Score Caps Applied

• None

Strengths

• Excellent data storytelling with clearly annotated gain and phase margins using distinct colors and marker shapes
• Strong aesthetic sophistication with custom color palette, themed backgrounds, and refined grid styling
• Correct title format and complete spec compliance with all required features
• Clean, well-structured code with deterministic data generation
• Good use of plotnine's grammar of graphics with faceted layout and layer composition

Weaknesses

• Severe layout imbalance between magnitude and phase panels — the magnitude panel has massive empty white space while the phase panel is extremely compressed, making its elements hard to read
• Phase panel crowding causes markers, annotations, and reference lines to cluster together
• The facet_wrap equal-height allocation doesn't suit this plot where panels need different vertical proportions

Issues Found

1. VQ-05 LOW: Severe panel height imbalance — magnitude panel wastes ~50% of its allocated space while phase panel is cramped
   • Fix: Consider adjusting the y-axis limits or using a different panel layout strategy to balance the two panels
2. VQ-02/VQ-03 MODERATE: Phase panel elements (markers, annotations, tick labels) are crowded due to compression
   • Fix: Better vertical space allocation would resolve this automatically

AI Feedback for Next Attempt

The primary issue is the facet panel height imbalance. The magnitude panel has excessive empty space while the phase panel is severely compressed. Consider limiting the magnitude y-axis range more tightly, or exploring alternative approaches to achieve more balanced panel proportions. The design excellence and data quality are strong — focus on layout.

Verdict: REJECTED