feat(highcharts): implement line-annotated-events

[github-actions]

Implementation: line-annotated-events - highcharts

Implements the highcharts version of line-annotated-events.

File: plots/line-annotated-events/implementations/highcharts.py

Parent Issue: #2997

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🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

The plot shows a time series line chart spanning January 2024 to late June 2024. A blue line (#306998) displays "Daily Active Users" data ranging from approximately 10,000 to 16,200 users, showing an overall upward trend with visible seasonality and noise. Five vertical dashed yellow lines (#FFD43B) mark key events: "Feature A Launch" (mid-January), "Marketing Campaign" (late February), "App Redesign" (late March), "Partnership Deal" (late April), and "Mobile Update" (late May). Each event is labeled at the top of the chart with alternating vertical positions to avoid overlap. Yellow circular markers with black outlines appear on the line at each event date. The title reads "line-annotated-events · highcharts · pyplots.ai" with a subtitle "Daily Active Users with Key Milestones". The x-axis shows monthly dates, y-axis shows "Daily Active Users", and a legend at the bottom identifies the two series.

Quality Score: 92/100

Criteria Checklist

Visual Quality (36/40 pts)

• VQ-01: Text Legibility (9/10) - Title, labels, and axis text are all clearly readable at large font sizes. Event labels are slightly smaller relative to plot size but still legible.
• VQ-02: No Overlap (8/8) - Event labels use alternating heights to avoid overlap, no text collisions detected.
• VQ-03: Element Visibility (7/8) - Line width is appropriate, event markers are clearly visible with good contrast. Line could be slightly thicker for optimal visibility.
• VQ-04: Color Accessibility (5/5) - Blue line and yellow markers are colorblind-safe, no red-green issues.
• VQ-05: Layout Balance (4/5) - Good use of canvas space, chart fills most of the area. Minor margin optimization possible.
• VQ-06: Axis Labels (2/2) - "Date" and "Daily Active Users" are descriptive.
• VQ-07: Grid & Legend (1/2) - Grid is subtle with dashed lines, legend is present. Legend could be more prominently sized.

Spec Compliance (25/25 pts)

• SC-01: Plot Type (8/8) - Correct line chart with event annotations.
• SC-02: Data Mapping (5/5) - Date on X-axis, values on Y-axis correctly assigned.
• SC-03: Required Features (5/5) - All spec features present: vertical event lines, markers at event points, text labels, distinct styling.
• SC-04: Data Range (3/3) - All data visible, axes show complete range.
• SC-05: Legend Accuracy (2/2) - Legend correctly identifies "Daily Active Users" and "Key Events".
• SC-06: Title Format (2/2) - Correct format: line-annotated-events · highcharts · pyplots.ai

Data Quality (18/20 pts)

• DQ-01: Feature Coverage (7/8) - Shows trend, seasonality, noise, and multiple events. Events are well-distributed across the timeline.
• DQ-02: Realistic Context (7/7) - User growth metrics with product milestones is a plausible, neutral business scenario.
• DQ-03: Appropriate Scale (4/5) - User counts from 10K-16K are realistic. Scale is sensible though values are somewhat round.

Code Quality (10/10 pts)

• CQ-01: KISS Structure (3/3) - Linear structure: imports → data → chart setup → series → export.
• CQ-02: Reproducibility (3/3) - Uses np.random.seed(42) for deterministic output.
• CQ-03: Clean Imports (2/2) - All imports are used.
• CQ-04: No Deprecated API (1/1) - Uses current highcharts-core API.
• CQ-05: Output Correct (1/1) - Saves as plot.png and plot.html.

Library Features (3/5 pts)

• LF-01: Uses distinctive library features (3/5) - Uses plotLines for event markers, scatter series for event points, datetime axis. Could better leverage Highcharts' native annotation features or tooltips.

Strengths

• Excellent implementation of event annotation pattern using plotLines with alternating label positions
• Clean colorblind-safe palette with blue line and yellow event markers
• Proper use of Highcharts datetime axis with appropriate label formatting
• Well-structured code following KISS principles with proper Selenium screenshot workflow
• Realistic business scenario with 5 distinct milestones across 180-day period

Weaknesses

• Legend text could be larger for better visibility at full resolution
• Could leverage Highcharts native annotation module for more sophisticated event labels
• Event marker scatter points could have tooltips showing event details for better interactivity in HTML output

Verdict: APPROVED