feat(pygal): implement cat-box-strip (#2763)

## Implementation: `cat-box-strip` - pygal

Implements the **pygal** version of `cat-box-strip`.

**File:** `plots/cat-box-strip/implementations/pygal.py`

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/20601060592)*

---------

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Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

plots/cat-box-strip/implementations/pygal.py

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+""" pyplots.ai
+cat-box-strip: Box Plot with Strip Overlay
+Library: pygal 3.1.0 | Python 3.13.11
+Quality: 91/100 | Created: 2025-12-30
+"""
+
+import numpy as np
+import pygal
+from pygal.style import Style
+
+
+# Data - Plant growth measurements (cm) under different light conditions
+np.random.seed(42)
+categories = ["Full Sun", "Partial Shade", "Full Shade", "Artificial"]
+data = {
+    "Full Sun": np.random.normal(45, 8, 35),
+    "Partial Shade": np.random.normal(38, 10, 40),
+    "Full Shade": np.random.normal(25, 6, 30),
+    "Artificial": np.random.normal(35, 12, 38),
+}
+
+# Add realistic variation and some outliers
+data["Full Sun"] = np.append(data["Full Sun"], [68, 72, 28])
+data["Partial Shade"] = np.append(data["Partial Shade"], [65, 15])
+data["Full Shade"] = np.append(data["Full Shade"], [42, 10])
+data["Artificial"] = np.append(data["Artificial"], [70, 12])
+
+# Group colors - distinct for each category (colorblind-safe)
+group_colors = ["#306998", "#FFD43B", "#4CAF50", "#E07B39"]
+
+# Build color sequence: 6 elements per box (box, median, 2 whiskers, 2 caps) + 1 strip = 7 per category
+# But we draw all boxes first (6*4=24), then all strips (4)
+# So color sequence needs: 6 of color1, 6 of color2, 6 of color3, 6 of color4, then 1 each for strips
+color_sequence = []
+for c in group_colors:
+    color_sequence.extend([c] * 6)  # 6 box elements per category
+for c in group_colors:
+    color_sequence.append(c)  # 1 strip series per category
+
+# Custom style for 4800x2700 px canvas
+custom_style = Style(
+    background="white",
+    plot_background="white",
+    foreground="#333333",
+    foreground_strong="#333333",
+    foreground_subtle="#999999",
+    guide_stroke_color="#e0e0e0",
+    colors=tuple(color_sequence),
+    title_font_size=72,
+    label_font_size=48,
+    major_label_font_size=44,
+    legend_font_size=44,
+    value_font_size=36,
+    opacity=0.6,
+    opacity_hover=0.8,
+)
+
+# Create XY chart for combined box plot with strip overlay
+# X-axis = Category position, Y-axis = Plant Height (cm)
+chart = pygal.XY(
+    width=4800,
+    height=2700,
+    style=custom_style,
+    title="cat-box-strip · pygal · pyplots.ai",
+    x_title="Light Condition",
+    y_title="Plant Height (cm)",
+    show_legend=False,
+    stroke=True,
+    fill=True,
+    dots_size=0,
+    show_x_guides=False,
+    show_y_guides=True,
+    xrange=(0, 5),
+    range=(0, 80),
+    margin=80,
+    explicit_size=True,
+)
+
+# Layout parameters
+box_width = 0.25
+cap_width = 0.15
+
+# Pre-compute all components
+strip_data = []
+box_data = []
+
+for i, (category, values) in enumerate(data.items()):
+    center_x = i + 1  # X position for this group (1, 2, 3, 4)
+    values = np.array(values)
+    color = group_colors[i]
+
+    # --- Box Plot Statistics ---
+    median = float(np.median(values))
+    q1 = float(np.percentile(values, 25))
+    q3 = float(np.percentile(values, 75))
+    iqr = q3 - q1
+    whisker_low = float(max(values.min(), q1 - 1.5 * iqr))
+    whisker_high = float(min(values.max(), q3 + 1.5 * iqr))
+    box_data.append((center_x, median, q1, q3, whisker_low, whisker_high, color))
+
+    # --- Strip Points with Jitter ---
+    np.random.seed(42 + i)
+    jitter = np.random.uniform(-0.12, 0.12, len(values))
+    strip_points = [(center_x + j, float(v)) for j, v in zip(jitter, values, strict=True)]
+    strip_data.append((category, strip_points, color))
+
+# First, draw box plots (so strip points appear on top)
+for center_x, median, q1, q3, whisker_low, whisker_high, _color in box_data:
+    # IQR box (filled rectangle)
+    quartile_box = [
+        (center_x - box_width, q1),
+        (center_x - box_width, q3),
+        (center_x + box_width, q3),
+        (center_x + box_width, q1),
+        (center_x - box_width, q1),
+    ]
+    chart.add("", quartile_box, stroke=True, fill=True, show_dots=False, stroke_style={"width": 6})
+
+    # Median line (horizontal line within box)
+    median_line = [(center_x - box_width * 1.1, median), (center_x + box_width * 1.1, median)]
+    chart.add("", median_line, stroke=True, fill=False, show_dots=False, stroke_style={"width": 10})
+
+    # Whiskers (vertical lines from box to caps)
+    whisker_bottom = [(center_x, q1), (center_x, whisker_low)]
+    whisker_top = [(center_x, q3), (center_x, whisker_high)]
+    chart.add("", whisker_bottom, stroke=True, fill=False, show_dots=False, stroke_style={"width": 6})
+    chart.add("", whisker_top, stroke=True, fill=False, show_dots=False, stroke_style={"width": 6})
+
+    # Whisker caps (horizontal lines at ends)
+    cap_bottom = [(center_x - cap_width, whisker_low), (center_x + cap_width, whisker_low)]
+    cap_top = [(center_x - cap_width, whisker_high), (center_x + cap_width, whisker_high)]
+    chart.add("", cap_bottom, stroke=True, fill=False, show_dots=False, stroke_style={"width": 6})
+    chart.add("", cap_top, stroke=True, fill=False, show_dots=False, stroke_style={"width": 6})
+
+# Add strip points on top with transparency
+for _category, strip_points, _color in strip_data:
+    chart.add("", strip_points, stroke=False, fill=False, dots_size=18)
+
+# X-axis labels for categories
+chart.x_labels = [
+    {"value": 0, "label": ""},
+    {"value": 1, "label": "Full Sun"},
+    {"value": 2, "label": "Partial Shade"},
+    {"value": 3, "label": "Full Shade"},
+    {"value": 4, "label": "Artificial"},
+    {"value": 5, "label": ""},
+]
+
+# Save outputs
+chart.render_to_file("plot.html")
+chart.render_to_png("plot.png")

plots/cat-box-strip/metadata/pygal.yaml

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+library: pygal
+specification_id: cat-box-strip
+created: '2025-12-30T16:31:18Z'
+updated: '2025-12-30T16:42:46Z'
+generated_by: claude-opus-4-5-20251101
+workflow_run: 20601060592
+issue: 0
+python_version: 3.13.11
+library_version: 3.1.0
+preview_url: https://storage.googleapis.com/pyplots-images/plots/cat-box-strip/pygal/plot.png
+preview_thumb: https://storage.googleapis.com/pyplots-images/plots/cat-box-strip/pygal/plot_thumb.png
+preview_html: https://storage.googleapis.com/pyplots-images/plots/cat-box-strip/pygal/plot.html
+quality_score: 91
+review:
+  strengths:
+  - Excellent creative solution using XY chart to achieve box plot with strip overlay
+    (pygal.Box does not support strip overlay natively)
+  - Well-designed color scheme with matching box and point colors for each category
+  - Good use of custom Style for proper font sizing at 4800x2700 resolution
+  - Clear statistical visualization with median, quartiles, whiskers, and caps properly
+    constructed
+  - Jitter and transparency on strip points effectively reduce overlap
+  weaknesses:
+  - Grid only shows on y-axis, no x-axis guides (minor visual consistency issue)
+  - Some strip points in dense areas still overlap slightly despite jitter