feat(plotly): implement scatter-regression-lowess

[github-actions]

Implementation: scatter-regression-lowess - plotly

Implements the plotly version of scatter-regression-lowess.

File: plots/scatter-regression-lowess/implementations/plotly.py

Parent Issue: #2855

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🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

The plot displays a scatter plot with LOWESS regression on a white background with a subtle grid. The title "scatter-regression-lowess · plotly · pyplots.ai" is centered at the top in dark gray text. Blue scatter points (Python Blue #306998) with moderate transparency (opacity 0.6) show a complex non-linear relationship - relatively flat from x=0 to x=4, then curving upward steeply from x=5 to x=10. A smooth yellow/gold LOWESS curve (Python Yellow #FFD43B) with width 4 overlays the data, clearly showing the underlying trend. The legend is positioned in the upper-left corner with "Data Points" and "LOWESS Curve" entries on a semi-transparent white background. X-axis is labeled "X Value" (0-10), Y-axis is labeled "Y Value" (-5 to 20). The layout uses a clean plotly_white template with light gray gridlines.

Quality Score: 91/100

Criteria Checklist

Visual Quality (36/40 pts)

• VQ-01: Text Legibility (10/10) - Title at 28pt, axis labels at 22pt, tick fonts at 18pt - all perfectly readable
• VQ-02: No Overlap (8/8) - No overlapping text elements anywhere
• VQ-03: Element Visibility (7/8) - Markers well-sized (size=10), good alpha (0.6) for 200 points; LOWESS line clearly visible with width=4
• VQ-04: Color Accessibility (5/5) - Blue (#306998) and Yellow (#FFD43B) have excellent contrast and are colorblind-safe
• VQ-05: Layout Balance (5/5) - Plot fills canvas well with balanced margins, good use of 16:9 aspect ratio
• VQ-06: Axis Labels (1/2) - Descriptive labels "X Value" and "Y Value" but no units
• VQ-07: Grid & Legend (2/2) - Subtle grid with rgba(0,0,0,0.1), legend well-placed in upper-left with semi-transparent background

Spec Compliance (25/25 pts)

• SC-01: Plot Type (8/8) - Correct scatter plot with LOWESS regression curve
• SC-02: Data Mapping (5/5) - X/Y correctly mapped on respective axes
• SC-03: Required Features (5/5) - All spec features present: LOWESS curve distinct from points (solid yellow line vs blue markers), moderate smoothing (frac=0.3), moderate transparency on points (0.6), descriptive title mentioning LOWESS
• SC-04: Data Range (3/3) - Axes show all data points without cutoff
• SC-05: Legend Accuracy (2/2) - Legend correctly identifies "Data Points" and "LOWESS Curve"
• SC-06: Title Format (2/2) - Uses exact format "scatter-regression-lowess · plotly · pyplots.ai"

Data Quality (18/20 pts)

• DQ-01: Feature Coverage (8/8) - Excellent: shows complex non-linear relationship with varying patterns across x-range (flat region, then steep curve), demonstrating why LOWESS is valuable
• DQ-02: Realistic Context (5/7) - Generic but plausible mathematical/scientific scenario; could benefit from a real-world context
• DQ-03: Appropriate Scale (5/5) - Sensible values, good spread showing the non-linear relationship

Code Quality (9/10 pts)

• CQ-01: KISS Structure (3/3) - Clean structure: imports → data → LOWESS calculation → plot → save
• CQ-02: Reproducibility (3/3) - np.random.seed(42) ensures reproducibility
• CQ-03: Clean Imports (2/2) - Only numpy and plotly.graph_objects used, both necessary
• CQ-04: No Deprecated API (1/1) - Uses current Plotly API
• CQ-05: Output Correct (0/0) - Saves as plot.png ✓ (already counted)

Library Features (3/5 pts)

• LF-01: Uses distinctive library features (3/5) - Uses go.Figure, go.Scatter with proper marker/line styling, interactive HTML export; however, implements LOWESS manually instead of using statsmodels.api.nonparametric.lowess which would be more idiomatic for Python

Strengths

• Excellent implementation of LOWESS algorithm from scratch with proper tricube weighting
• Clear visual distinction between scatter points (blue, transparent) and LOWESS curve (yellow, solid line)
• Perfect title format and professional plotly_white template
• Good font sizes throughout ensuring readability at 4800x2700 resolution
• Well-chosen smoothing fraction (0.3) that captures the trend without overfitting

Weaknesses

• Axis labels lack units or more descriptive context (e.g., could use domain-specific labels)
• Manual LOWESS implementation is educational but verbose; could leverage statsmodels for production code

Verdict: APPROVED