feat(pygal): implement streamline-basic

[github-actions]

Implementation: streamline-basic - pygal

Implements the pygal version of streamline-basic.

File: plots/streamline-basic/implementations/pygal.py

Parent Issue: #2861

---

🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

The plot displays a vortex flow field visualization with concentric circular/spiral streamlines radiating from the center. Five color-coded series are shown: Inner (dark blue #306998), Near-Inner (light blue #3d8cc7), Middle (cyan #5ab4dc), Near-Outer (orange #e6a020), and Outer (gold #FFD43B). The streamlines trace counterclockwise paths through the field, with inner streamlines being tighter circles and outer ones being larger ellipses. The title "streamline-basic · pygal · pyplots.ai" appears at top. Axes are labeled "X Position" and "Y Position" with range -3 to 3. The legend is positioned at the bottom with all 5 categories displayed horizontally.

Quality Score: 72/100

Criteria Checklist

Visual Quality (29/40 pts)

• VQ-01: Text Legibility (8/10) - Title and axis labels readable, font sizes appropriate for 4800x2700
• VQ-02: No Overlap (8/8) - No overlapping text elements
• VQ-03: Element Visibility (5/8) - Streamlines visible but some overlap heavily in center; line width good
• VQ-04: Color Accessibility (4/5) - Good color progression from blue to gold, distinguishable
• VQ-05: Layout Balance (3/5) - Plot uses ~70% of canvas width but appears compressed vertically due to 16:9 ratio
• VQ-06: Axis Labels (1/2) - Descriptive labels without units (position is unitless for mathematical field, acceptable)
• VQ-07: Grid & Legend (0/2) - Grid is quite subtle but legend items have tiny markers that are hard to see

Spec Compliance (20/25 pts)

• SC-01: Plot Type (5/8) - Approximates streamlines using XY line series; pygal lacks native streamline support so this is a reasonable workaround, but not true streamlines
• SC-02: Data Mapping (5/5) - X/Y correctly mapped to position coordinates
• SC-03: Required Features (4/5) - Shows vortex flow pattern and color encoding by radial distance; missing velocity magnitude coloring along streamlines
• SC-04: Data Range (3/3) - Axes show full -3.5 to 3.5 range, all data visible
• SC-05: Legend Accuracy (1/2) - Labels describe radial bins but "Inner/Outer" could be more descriptive
• SC-06: Title Format (2/2) - Correct format: "{spec-id} · {library} · pyplots.ai"

Data Quality (15/20 pts)

• DQ-01: Feature Coverage (6/8) - Shows circular flow pattern and radial variation; could show more diverse field structure
• DQ-02: Realistic Context (5/7) - Mathematical vortex field is a classic physics example, plausible
• DQ-03: Appropriate Scale (4/5) - Coordinate range and streamline density appropriate

Code Quality (5/10 pts)

• CQ-01: KISS Structure (0/3) - Uses functions (get_velocity, trace_streamline) which violates KISS principle
• CQ-02: Reproducibility (3/3) - Uses np.random.seed(42)
• CQ-03: Clean Imports (2/2) - Only imports numpy, pygal, and Style (all used)
• CQ-04: No Deprecated API (0/1) - Uses strict=False in zip which is fine but docstrings in functions not typical for plot scripts
• CQ-05: Output Correct (0/1) - Saves both plot.png and plot.html (correct)

Library Features (3/5 pts)

• LF-01: Uses distinctive library features (3/5) - Uses XY chart, custom Style, stroke_style, legend_at_bottom; reasonable usage but no special pygal features beyond basics

Strengths

• Creative workaround for streamline visualization using XY series with None separators
• Good color progression from blue (inner) to gold (outer) representing radial distance
• Proper title format and axis labeling
• Seed set for reproducibility
• Clean visual output with balanced layout

Weaknesses

• Code uses helper functions (get_velocity, trace_streamline) instead of flat KISS structure
• Streamlines are connected line segments rather than smooth curves, visible jaggedness
• Center of vortex shows heavy overlapping of streamlines making it cluttered
• Legend marker dots are very small compared to the line widths in the plot

Verdict: REJECTED

The implementation shows good creativity in approximating streamlines with pygal's XY chart limitations, but the code structure violates KISS principles by using functions. The visual result is acceptable but not publication-quality due to line jaggedness and center clutter.

[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 circular streamlines representing a vortex flow field on a white background. The title "streamline-basic · pygal · pyplots.ai" appears at the top. The X and Y axes are labeled "X Position" and "Y Position" respectively, ranging from -3 to 3. Multiple concentric elliptical/circular streamlines are shown in different colors: blue tones (Inner and Near-Inner in light blue), and yellow/gold tones (Middle, Near-Outer, and Outer). A legend at the bottom shows 5 categories: Inner, Near-Inner, Middle, Near-Outer, and Outer. The streamlines form a counterclockwise spiral pattern emanating from the center, with inner rings in blue and outer rings transitioning to yellow/gold.

Quality Score: 75/100

Criteria Checklist

Visual Quality (32/40 pts)

• VQ-01: Text Legibility (8/10) - Title and axis labels readable, tick labels slightly small but acceptable
• VQ-02: No Overlap (8/8) - No overlapping text or elements
• VQ-03: Element Visibility (6/8) - Streamlines visible but line width could be thicker for better visibility
• VQ-04: Color Accessibility (3/5) - Blue and yellow distinguishable but 5 colors reduces clarity; two blues are too similar
• VQ-05: Layout Balance (4/5) - Good canvas utilization, plot fills adequate space
• VQ-06: Axis Labels (1/2) - Descriptive labels but missing units (though position may not need units)
• VQ-07: Grid & Legend (2/2) - Grid subtle, legend well placed at bottom

Spec Compliance (20/25 pts)

• SC-01: Plot Type (6/8) - Uses XY lines to simulate streamlines; pygal lacks native streamline support, this is a reasonable approximation
• SC-02: Data Mapping (5/5) - X/Y coordinates correctly assigned for flow visualization
• SC-03: Required Features (3/5) - Shows flow pattern but missing velocity magnitude color encoding as suggested in spec
• SC-04: Data Range (3/3) - Axes show full data range
• SC-05: Legend Accuracy (1/2) - Legend labels differ from code (code has "Inner (r=1.0)" etc., image shows "Inner", "Near-Inner" etc. - mismatch)
• SC-06: Title Format (2/2) - Correct format: streamline-basic · pygal · pyplots.ai

Data Quality (13/20 pts)

• DQ-01: Feature Coverage (5/8) - Shows circular vortex flow but only single flow pattern, no variation in field structure
• DQ-02: Realistic Context (5/7) - Vortex flow is plausible physics scenario but generic
• DQ-03: Appropriate Scale (3/5) - Coordinate values appropriate but abstract without physical context

Code Quality (8/10 pts)

• CQ-01: KISS Structure (3/3) - Simple linear structure, no functions/classes
• CQ-02: Reproducibility (3/3) - np.random.seed(42) set (though not strictly needed for deterministic vortex)
• CQ-03: Clean Imports (1/2) - numpy imported but random.seed not functionally used in deterministic calculation
• CQ-04: No Deprecated API (1/1) - Uses current pygal API
• CQ-05: Output Correct (0/1) - Saves both plot.png and plot.html (correct)

Library Features (2/5 pts)

• LF-01: Uses distinctive library features (2/5) - Uses XY chart and custom styling, but pygal's SVG/interactive features not fully leveraged

Strengths

• Clean circular vortex pattern clearly visualizes flow field topology
• Good use of pygal XY chart to approximate streamlines without native support
• Large font sizes appropriate for 4800x2700 canvas
• Legend at bottom with multiple columns avoids plot obstruction
• White background with subtle grid provides clean presentation

Weaknesses

• Legend labels in output ("Inner", "Near-Inner", etc.) do not match the code definition ("Inner (r=1.0)", "Mid-Inner (r=1.5)", etc.) - investigate cairosvg rendering or pygal label handling
• Two blue colors (Inner and Near-Inner) are very similar and hard to distinguish - use more contrasting colors
• Only 4 radii in code but legend shows 5 categories - synchronize legend with actual data series
• Spec suggests color encoding velocity magnitude along streamlines, but current implementation uses radial distance for color

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 vortex streamline visualization using concentric circular/spiral patterns. The title "streamline-basic · pygal · pyplots.ai" is clearly visible at the top. The X and Y axes are labeled "X Position" and "Y Position" respectively, ranging from -3 to 3. The streamlines are colored in two main color groups - light blue/cyan tones for inner regions and tan/yellow/orange tones for outer regions. A legend appears at the bottom with 5 categories. The circular flow pattern correctly represents a vortex field (u = -y, v = x), with streamlines spiraling counterclockwise around the origin.

Quality Score: 75/100

Criteria Checklist

Visual Quality (31/40 pts)

• VQ-01: Text Legibility (8/10) - Title and axis labels are readable, though legend text at bottom is quite small relative to the large canvas
• VQ-02: No Overlap (8/8) - No overlapping text elements
• VQ-03: Element Visibility (6/8) - Streamlines visible but thin; outer streamlines use similar colors making some harder to distinguish
• VQ-04: Color Accessibility (3/5) - Colors differentiate regions but blue/cyan shades are somewhat similar; not optimally colorblind-safe
• VQ-05: Layout Balance (4/5) - Good use of canvas space, plot is centered with appropriate margins
• VQ-06: Axis Labels (1/2) - Descriptive labels but no units (position is unitless so this is acceptable)
• VQ-07: Grid & Legend (1/2) - Grid present but legend categories don't match code (code has 4 categories but image shows 5)

Spec Compliance (21/25 pts)

• SC-01: Plot Type (6/8) - Creative approximation of streamlines using XY lines; pygal lacks native streamline support so this is a reasonable workaround, but not a true streamline plot
• SC-02: Data Mapping (5/5) - X/Y coordinates correctly mapped for vortex field
• SC-03: Required Features (4/5) - Shows flow patterns and circular streamlines; color encoding present but represents radius not velocity magnitude as spec suggests
• SC-04: Data Range (3/3) - Axes show full -3 to 3 range
• SC-05: Legend Accuracy (1/2) - Legend present but labels in image don't match code exactly
• SC-06: Title Format (2/2) - Correct format: streamline-basic · pygal · pyplots.ai

Data Quality (15/20 pts)

• DQ-01: Feature Coverage (6/8) - Shows vortex pattern well with multiple radial levels; demonstrates flow topology but could show more variation
• DQ-02: Realistic Context (5/7) - Vortex flow is a plausible physics scenario, though labels like "Slow/Fast Flow" don't accurately describe vortex behavior (flow speed is actually higher at inner radii in a free vortex)
• DQ-03: Appropriate Scale (4/5) - Values are reasonable for a normalized vector field

Code Quality (8/10 pts)

• CQ-01: KISS Structure (3/3) - No functions or classes, follows imports → data → plot → save pattern
• CQ-02: Reproducibility (3/3) - np.random.seed(42) present
• CQ-03: Clean Imports (2/2) - Only numpy, pygal, and Style imported
• CQ-04: No Deprecated API (0/1) - Unable to verify
• CQ-05: Output Correct (1/1) - Saves as plot.png and plot.html

Library Features (0/5 pts)

• LF-01: Uses distinctive library features (0/5) - Uses basic XY chart; doesn't leverage pygal-specific features beyond basic line plotting

Strengths

• Creative workaround for pygal's lack of native streamline support using XY line plots
• Correct vortex flow field implementation (u = -y, v = x)
• Clean KISS code structure with appropriate comments
• Good use of canvas space and readable title/labels
• Reproducible with fixed random seed

Weaknesses

• Legend labels in rendered image appear inconsistent with code (5 categories shown vs 4 in code)
• Color scheme uses similar shades (blue tones, tan tones) that reduce distinguishability
• Streamlines are thin relative to the large canvas size
• Flow speed labeling ("Slow/Fast Flow") is physically inaccurate for vortex flow where inner radii have higher angular velocity

Verdict: APPROVED

This is attempt 3/3 with a score of 75/100, which exceeds the minimum threshold of 50 for final merge. While there are some visual and labeling inconsistencies, the implementation demonstrates a creative and functional approach to representing streamlines in a library that lacks native support for this plot type.

[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 displays concentric circular/elliptical streamlines representing a vortex flow field centered at the origin. The visualization shows 5 distinct orbital groups distinguished by color: red "Inner" orbits closest to center, light blue "Near-Inner" orbits, blue "Middle" orbits, pale yellow/tan "Near-Outer" orbits, and golden yellow "Outer" orbits at the largest radii. The streamlines form smooth closed curves that demonstrate the counterclockwise circular flow pattern (u=-y, v=x). The title reads "streamline-basic · pygal · pyplots.ai" at the top, with "X Position" and "Y Position" axis labels. A legend at the bottom shows the 5 orbital categories. The axes range from -3 to 3 on both dimensions. Grid lines are subtle and the overall layout is clean with good use of the canvas.

Quality Score: 77/100

Criteria Checklist

Visual Quality (32/40 pts)

• VQ-01: Text Legibility (8/10) - Title, axis labels, and legend are readable but tick labels could be slightly larger
• VQ-02: No Overlap (8/8) - No overlapping text elements
• VQ-03: Element Visibility (6/8) - Streamlines are visible but the many overlapping lines at similar radii create visual density; line thickness is good
• VQ-04: Color Accessibility (4/5) - Good use of distinct colors (red, blue, yellow) but the Near-Inner/Middle blue tones are somewhat similar
• VQ-05: Layout Balance (4/5) - Good canvas utilization, streamlines fill the plot area well
• VQ-06: Axis Labels (1/2) - Descriptive labels "X Position" and "Y Position" but no units
• VQ-07: Grid & Legend (1/2) - Grid is subtle, legend is at bottom but labels are truncated (showing only "Inner", "Near-Inner", etc. without full context)

Spec Compliance (22/25 pts)

• SC-01: Plot Type (6/8) - This is an approximation of streamlines using XY line plots; pygal lacks native streamline support so this connected-line approach is a reasonable workaround, though not true streamlines
• SC-02: Data Mapping (5/5) - X/Y coordinates correctly mapped to vortex flow field
• SC-03: Required Features (5/5) - Shows flow patterns, multiple starting points, continuous curves
• SC-04: Data Range (3/3) - Axes show full data range from -3 to 3
• SC-05: Legend Accuracy (1/2) - Legend labels are somewhat misleading (code uses "Inner Orbit", "Mid-Inner Orbit" etc. but rendered shows shorter versions)
• SC-06: Title Format (2/2) - Correct format "streamline-basic · pygal · pyplots.ai"

Data Quality (13/20 pts)

• DQ-01: Feature Coverage (5/8) - Shows circular vortex pattern but all streamlines follow similar closed orbits; lacks variation like saddle points or sources/sinks that would demonstrate more flow features
• DQ-02: Realistic Context (5/7) - Vortex flow is a valid physics example but generic; could benefit from more specific application context
• DQ-03: Appropriate Scale (3/5) - Arbitrary units, -3 to 3 range is reasonable for demonstration

Code Quality (7/10 pts)

• CQ-01: KISS Structure (3/3) - No functions/classes, follows imports → data → plot → save pattern
• CQ-02: Reproducibility (3/3) - Uses np.random.seed(42)
• CQ-03: Clean Imports (0/2) - numpy import used but random seed not actually needed for this deterministic vortex field
• CQ-04: No Deprecated API (1/1) - No deprecated functions
• CQ-05: Output Correct (0/1) - Saves both plot.png and plot.html correctly

Library Features (3/5 pts)

• LF-01: Uses distinctive library features (3/5) - Uses pygal XY chart with custom styling and legend_at_bottom, but doesn't leverage advanced pygal features like tooltips or animation

Strengths

• Creative workaround for pygal's lack of native streamline support using XY connected lines
• Good visual representation of vortex flow with distinct colored orbital groups
• Clean code structure following KISS principles
• Appropriate use of custom Style for font sizing and colors
• Good canvas utilization with balanced layout
• Correct title format

Weaknesses

• Legend labels in the rendered image appear truncated compared to the code-defined labels
• The blue color tones (Near-Inner and Middle) are somewhat similar and could be more distinct
• Streamlines only show closed circular orbits; more varied flow features would better demonstrate streamline capabilities
• Random seed is set but not actually needed since the vortex field is mathematically deterministic

Verdict: APPROVED

This is attempt 3/3. While the score is 77/100 (below the 90 threshold for immediate approval), it exceeds the 50-point minimum required for merge after 3 attempts. The implementation represents a reasonable creative solution given pygal's limitations for this plot type.

[github-actions]

AI Review - Final Status

Score: 77/100 (Acceptable)

After 3 repair attempts, pygal reached 77/100.

Score ≥ 50 is acceptable for the repository. Merging.

---

🤖 impl-review