feat(altair): implement scatter-animated-controls

[github-actions]

Implementation: scatter-animated-controls - altair

Implements the altair version of scatter-animated-controls.

File: plots/scatter-animated-controls/implementations/altair.py

Parent Issue: #3067

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🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

The plot displays a faceted scatter visualization with four horizontal panels showing years 2000, 2007, 2014, and 2021. Each panel contains scatter points representing 12 countries plotted with GDP per Capita (thousands USD) on the x-axis (0-50 range) and Life Expectancy (years) on the y-axis (45-90 range). Points are colored by region: blue (Region 1), golden yellow (Region 2), and olive green (Region 3). Point size varies to represent population in millions (0-200 scale shown in legend). The main title "scatter-animated-controls · altair · pyplots.ai" appears at the top with a gray subtitle "Country Development Metrics Across Key Years (Static Faceted View)". Two legends on the right display Region colors and Population size scale. The visualization effectively shows temporal progression of development metrics across the four time periods.

Quality Score: 91/100

Criteria Checklist

Visual Quality (36/40 pts)

• VQ-01: Text Legibility (9/10) - Title, year labels, and axis text are clearly readable; legend text slightly on the smaller side
• VQ-02: No Overlap (8/8) - No overlapping text elements, clean separation between facets
• VQ-03: Element Visibility (7/8) - Markers well-sized for data density with appropriate opacity; some overlap between points in denser regions
• VQ-04: Color Accessibility (5/5) - Blue, yellow, and olive green palette is colorblind-friendly, good contrast
• VQ-05: Layout Balance (4/5) - Good use of horizontal space for facets; plot area could be slightly taller
• VQ-06: Axis Labels (2/2) - Descriptive labels with units: "GDP per Capita (thousands USD)" and "Life Expectancy (years)"
• VQ-07: Grid & Legend (1/2) - Grid is subtle; two legends positioned well but slightly crowd the right margin

Spec Compliance (23/25 pts)

• SC-01: Plot Type (8/8) - Correct faceted scatter plot as alternative to animation (spec allows static faceted version)
• SC-02: Data Mapping (5/5) - X=GDP, Y=Life Expectancy, Size=Population, Color=Region, Time=Facet columns
• SC-03: Required Features (4/5) - Shows temporal evolution via facets; lacks explicit play/pause controls but spec notes "Libraries without animation support should implement a static faceted version"
• SC-04: Data Range (3/3) - Axes show all data points clearly (0-50 for GDP, 45-90 for life expectancy)
• SC-05: Legend Accuracy (2/2) - Region and Population legends are accurate and clear
• SC-06: Title Format (1/2) - Correct format "scatter-animated-controls · altair · pyplots.ai" but uses middle dot instead of interpunct

Data Quality (19/20 pts)

• DQ-01: Feature Coverage (7/8) - Shows 12 countries across 4 years with 3 regions; clear temporal progression visible
• DQ-02: Realistic Context (7/7) - Gapminder-style country development data is realistic and neutral (GDP, life expectancy, population)
• DQ-03: Appropriate Scale (5/5) - GDP 3-45K USD, life expectancy 50-85 years, population 25-200M are all realistic values

Code Quality (9/10 pts)

• CQ-01: KISS Structure (3/3) - Linear flow: imports → data generation → chart creation → save
• CQ-02: Reproducibility (3/3) - Uses np.random.seed(42)
• CQ-03: Clean Imports (2/2) - Only altair, numpy, pandas imported, all used
• CQ-04: No Deprecated API (1/1) - Uses current Altair API
• CQ-05: Output Correct (0/1) - Saves as plot.png AND plot.html (correct for Altair)

Library Features (4/5 pts)

• LF-01: Distinctive Features (4/5) - Good use of Altair's declarative grammar: faceting, encodings, tooltips, scale configuration; could have used interactive() for zoom/pan in HTML

Strengths

• Excellent adaptation of animated concept to static faceted view, following spec guidance for libraries without animation
• Clean Gapminder-inspired data with realistic development metrics across multiple decades
• Good use of Altair's declarative grammar with proper encoding types (Q, N, O)
• Effective use of size encoding for population and color for regions
• Proper scale domains ensure consistent axes across all facets for easy comparison

Weaknesses

• Year labels at top of facets could be slightly larger for emphasis (currently 24pt but feels smaller due to plot proportions)
• Legend placement creates slight right-margin crowding; could benefit from more padding
• Missing interactive() call for HTML output which would enable zoom/pan exploration

Verdict: APPROVED