feat(pygal): implement ecdf-basic (#5360)

## Implementation: `ecdf-basic` - python/pygal

Implements the **python/pygal** version of `ecdf-basic`.

**File:** `plots/ecdf-basic/implementations/python/pygal.py`

**Parent Issue:** #976

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/anyplot/actions/runs/24891020304)*

---------

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

Author: github-actions[bot]

plots/ecdf-basic/implementations/python/pygal.py

@@ -1,73 +1,116 @@
-""" pyplots.ai
+""" anyplot.ai
 ecdf-basic: Basic ECDF Plot
-Library: pygal 3.1.0 | Python 3.13.11
-Quality: 93/100 | Created: 2025-12-17
+Library: pygal 3.1.0 | Python 3.14.4
+Quality: 87/100 | Created: 2026-04-24
 """
 
-import numpy as np
-import pygal
-from pygal.style import Style
+import os
+import sys
 
 
-# Data
+# Script filename shadows the installed `pygal` package when run as `python pygal.py`;
+# dropping the script directory from sys.path lets the real package resolve.
+sys.path.pop(0)
+
+import numpy as np  # noqa: E402
+import pygal  # noqa: E402
+from pygal.style import Style  # noqa: E402
+
+
+# Theme tokens
+THEME = os.getenv("ANYPLOT_THEME", "light")
+PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
+INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
+INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
+INK_MUTED = "#6B6A63" if THEME == "light" else "#A8A79F"
+BRAND = "#009E73"
+ACCENT = "#D55E00"
+
+# Data — 120 food-delivery times (minutes); right-skewed gamma is realistic for
+# real order-to-door durations (mean ≈ 30 min, long right tail for outliers).
 np.random.seed(42)
-values = np.random.randn(100)
+delivery_times = np.random.gamma(shape=6.0, scale=5.0, size=120)
 
-# Calculate ECDF
-sorted_values = np.sort(values)
+# ECDF: sorted values on x, cumulative proportion (k/n) on y
+sorted_values = np.sort(delivery_times)
 n = len(sorted_values)
 ecdf_y = np.arange(1, n + 1) / n
 
-# Build step function data for XY chart
-# Each point needs to create a horizontal step then a vertical step
-xy_data = []
+# Step function: horizontal lead-in at y=0, then each observation adds a vertical
+# jump followed by a horizontal segment.
+x_lead = float(sorted_values[0]) - 2.0
+step_points = [(x_lead, 0.0), (float(sorted_values[0]), 0.0)]
 for i in range(n):
-    if i == 0:
-        # First point: start from (value, 0) to show initial step
-        xy_data.append((sorted_values[i], 0))
-    else:
-        # Horizontal line from previous point to current x
-        xy_data.append((sorted_values[i], ecdf_y[i - 1]))
-    # Vertical step up to current y
-    xy_data.append((sorted_values[i], ecdf_y[i]))
+    step_points.append((float(sorted_values[i]), float(ecdf_y[i])))
+    x_next = float(sorted_values[i + 1]) if i + 1 < n else float(sorted_values[-1]) + 2.0
+    step_points.append((x_next, float(ecdf_y[i])))
+
+# Quartile reference markers: P25, median, P75 — let readers read percentiles directly
+p25 = float(np.percentile(delivery_times, 25))
+p50 = float(np.percentile(delivery_times, 50))
+p75 = float(np.percentile(delivery_times, 75))
 
-# Extend to the right edge for completeness
-xy_data.append((sorted_values[-1] + 0.5, ecdf_y[-1]))
+font = "DejaVu Sans, Helvetica, Arial, sans-serif"
 
-# Custom style for 4800x2700 px canvas
 custom_style = Style(
-    background="white",
-    plot_background="white",
-    foreground="#333",
-    foreground_strong="#333",
-    foreground_subtle="#666",
-    colors=("#306998",),
+    background=PAGE_BG,
+    plot_background=PAGE_BG,
+    foreground=INK_SOFT,
+    foreground_strong=INK,
+    foreground_subtle=INK_MUTED,
+    colors=(BRAND, ACCENT),
+    font_family=font,
+    title_font_family=font,
+    label_font_family=font,
+    major_label_font_family=font,
+    legend_font_family=font,
+    tooltip_font_family=font,
     title_font_size=72,
-    label_font_size=48,
-    major_label_font_size=42,
-    legend_font_size=42,
-    value_font_size=36,
+    label_font_size=52,
+    major_label_font_size=44,
+    legend_font_size=40,
+    tooltip_font_size=32,
+    value_font_size=30,
+    stroke_opacity=1,
+    stroke_opacity_hover=1,
+    opacity=1,
+    opacity_hover=1,
+    stroke_width=28,
 )
 
-# Create XY chart (scatter-like with lines for step function)
 chart = pygal.XY(
     width=4800,
     height=2700,
     style=custom_style,
-    title="ecdf-basic · pygal · pyplots.ai",
-    x_title="Value",
+    title="ecdf-basic · pygal · anyplot.ai",
+    x_title="Delivery Time (minutes)",
     y_title="Cumulative Proportion",
     show_dots=False,
-    stroke_style={"width": 4},
     show_x_guides=True,
     show_y_guides=True,
     show_legend=False,
     range=(0, 1.05),
+    x_labels_major_count=9,
+    y_labels_major_count=6,
+    value_formatter=lambda v: f"{v:.2f}",
+    x_value_formatter=lambda v: f"{v:.0f}",
+    margin=60,
+    js=[],
 )
 
-# Add ECDF data
-chart.add("ECDF", xy_data)
+chart.add("ECDF", step_points)
+chart.add(
+    "Quartiles",
+    [
+        {"value": (p25, 0.25), "label": f"P25 = {p25:.1f} min"},
+        {"value": (p50, 0.50), "label": f"Median = {p50:.1f} min"},
+        {"value": (p75, 0.75), "label": f"P75 = {p75:.1f} min"},
+    ],
+    stroke=False,
+    show_dots=True,
+    dots_size=40,
+)
 
-# Save outputs
-chart.render_to_file("plot.html")
-chart.render_to_png("plot.png")
+chart.render_to_png(f"plot-{THEME}.png")
+with open(f"plot-{THEME}.html", "wb") as f:
+    f.write(chart.render())