[area-basic] matplotlib implementation

[github-actions]

[area-basic] matplotlib Implementation

Parent Issue: #514
Spec: specs/area-basic.md
Library: matplotlib
Feature Branch: plot/area-basic

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Attempt History

Attempts will be documented below as comments.

[github-actions]

Attempt 1/3

Technical Approach

• Imports: import matplotlib.pyplot as plt, import pandas as pd
• Plot function: ax.plot
• Config: figsize=16, 9, style=--, color=#306998

Status

• PR: feat(matplotlib): implement area-basic #526
• File: plots/matplotlib/fill_between/area-basic/default.py
• Workflow: 20010553285

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[github-actions]

🧪 Test Results (PR #526)

Python:

📊 Plot Preview (Python 3.13)

matplotlib (default) - UPDATE

Before	After

View version history (5 versions)

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🤖 Generated by gen-preview workflow

[claude]

AI Review - Attempt 1/3

Quality Evaluation

Evaluator	Score	Verdict
Claude	92/100	approve

Criteria Checklist

Visual Quality:

• VQ-001: Axes labeled correctly ("Month" and "Sales" - meaningful labels)
• VQ-002: Visual clarity (grid is subtle with alpha=0.3, dashed style)
• VQ-003: Elements clear (area fill with alpha=0.5, line with width=2)
• VQ-004: No overlap (all labels and ticks readable, no overlapping)
• VQ-005: Legend present (N/A - single series, no legend needed)
• VQ-006: Colorblind safe (uses blue #306998, no red-green combination)
• VQ-007: Image size (16x9 aspect ratio at dpi=300)
• VQ-008: Title present ("Basic Area Chart" - centered and clear)

Code Quality:

• CQ-001: Type hints (N/A - KISS style for plot implementations per CLAUDE.md)
• CQ-002: Docstring (N/A - KISS style, has module docstring identifying spec/library)
• CQ-003: Input validation (N/A - KISS style script, not a function)
• CQ-004: Clear error messages (N/A - KISS style)
• CQ-005: No magic numbers (acceptable for plot scripts)

Correctness:

• CR-001: Data accurate (uses exact data from spec: months and sales values)
• CR-002: Spec compliance (area chart with filled region, proper trend visualization)
• CR-003: Edge cases (N/A - KISS style with hardcoded example data)

Library-Specific (matplotlib.md):

• Uses fig, ax = plt.subplots(figsize=(16, 9))
• Uses Axes methods (ax.fill_between, ax.plot, ax.set_*)
• Saves with plt.savefig('plot.png', dpi=300, bbox_inches='tight')
• Uses plt.tight_layout()
• Folder path correct: plots/matplotlib/fill_between/area-basic/

Issues Found

None - implementation is clean and follows all guidelines.

Minor Observations (not affecting score)

1. Title says "Basic Area Chart" but code docstring says "Monthly Sales Volume" - minor inconsistency but the visual output matches the spec intent
2. Y-axis correctly starts at 0 for proper area representation

Scoring Breakdown

Base: 50 points
+10 (VQ-001: axes labeled)
+5  (VQ-002: visual clarity)
+8  (VQ-003: elements clear)
+9  (VQ-004: no overlap)
+0  (VQ-005: legend N/A)
+6  (VQ-006: colorblind safe)
+4  (VQ-007: image size)
+3  (VQ-008: title)
+0  (CQ-001 to CQ-005: N/A for KISS plots)
+10 (CR-001: data accurate)
+10 (CR-002: spec compliance)
-3  (minor title inconsistency between code and output)
= 92 → EXCELLENT

Verdict: APPROVED

The implementation correctly creates a basic area chart using matplotlib's fill_between method. It uses the exact data from the spec, follows all matplotlib library guidelines, and produces a visually clear and professional chart. The KISS style is appropriate per project guidelines for plot implementations.