feat(matplotlib): implement radar-multi (#10298)

## Implementation: `radar-multi` - python/matplotlib

Implements the **python/matplotlib** version of `radar-multi`.

**File:** `plots/radar-multi/implementations/python/matplotlib.py`

**Parent Issue:** #2026

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/anyplot/actions/runs/32046021626)*

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Markus Neusinger <2921697+MarkusNeusinger@users.noreply.github.com>

Author: github-actions[bot]

plots/radar-multi/implementations/python/matplotlib.py

@@ -1,7 +1,7 @@
 """ anyplot.ai
 radar-multi: Multi-Series Radar Chart
-Library: matplotlib 3.10.9 | Python 3.13.13
-Quality: 91/100 | Updated: 2026-05-07
+Library: matplotlib 3.11.1 | Python 3.13.15
+Quality: 86/100 | Updated: 2026-08-17
 """
 
 import os
@@ -17,16 +17,17 @@
 INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
 INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
 
-# Okabe-Ito palette (first three series)
+# Imprint palette (first three series, canonical order)
 IMPRINT = ["#009E73", "#C475FD", "#4467A3"]
 
-# Data: Product comparison across key attributes
+# Data: product comparison across key attributes — Product B is the overall leader
 categories = ["Performance", "Battery Life", "Camera", "Display", "Build Quality", "Value"]
 products = {
     "Product A": [85, 70, 90, 88, 75, 65],
     "Product B": [72, 95, 78, 82, 88, 80],
     "Product C": [90, 60, 85, 75, 70, 90],
 }
+leader_idx = 1  # Product B carries the highest average score — given visual emphasis
 
 # Number of variables
 n_categories = len(categories)
@@ -36,38 +37,95 @@
 angles += angles[:1]  # Close the polygon
 
 # Create figure (square format for radar)
-fig, ax = plt.subplots(figsize=(10, 10), subplot_kw={"polar": True}, facecolor=PAGE_BG)
+fig, ax = plt.subplots(figsize=(6, 6), dpi=400, subplot_kw={"polar": True}, facecolor=PAGE_BG)
 ax.set_facecolor(PAGE_BG)
 
+# Orient the radar with the first category at the top, going clockwise, so
+# no category label lands due-east where the legend sits
+ax.set_theta_zero_location("N")
+ax.set_theta_direction(-1)
+
+# Per-series visual weight — the leader draws bolder and on top, guiding the eye
+# to the strongest overall performer without adding any text annotation
+markers = ["o", "s", "^"]
+linewidths = [2.5, 2.5, 2.5]
+markersizes = [8, 8, 8]
+fill_alphas = [0.18, 0.18, 0.18]
+zorders = [1, 1, 1]  # below the default radial-grid/tick-label zorder (~2.5)
+linewidths[leader_idx] = 3.5
+markersizes[leader_idx] = 12
+fill_alphas[leader_idx] = 0.35
+zorders[leader_idx] = 1.5
+
 # Plot each product
 for idx, (product, values) in enumerate(products.items()):
     values_closed = values + values[:1]  # Close the polygon
-    ax.plot(angles, values_closed, "o-", linewidth=3, label=product, color=IMPRINT[idx], markersize=10)
-    ax.fill(angles, values_closed, alpha=0.25, color=IMPRINT[idx])
-
-# Set category labels at each axis
+    ax.plot(
+        angles,
+        values_closed,
+        marker=markers[idx],
+        linestyle="-",
+        linewidth=linewidths[idx],
+        label=product,
+        color=IMPRINT[idx],
+        markersize=markersizes[idx],
+        markeredgecolor=PAGE_BG,
+        markeredgewidth=1,
+        zorder=zorders[idx],
+    )
+    ax.fill(angles, values_closed, alpha=fill_alphas[idx], color=IMPRINT[idx], zorder=zorders[idx])
+
+# Set category labels at each axis, nudged outward and aligned by their
+# rendered screen position (accounting for the N-zero/clockwise rotation
+# above) so labels on the right lean left, labels on the left lean right,
+# and top/bottom labels stay centered — none collide with their own markers
 ax.set_xticks(angles[:-1])
-ax.set_xticklabels(categories, fontsize=18, fontweight="bold", color=INK)
-
-# Set radial grid
+tick_labels = ax.set_xticklabels(categories, fontsize=13, fontweight="bold", color=INK)
+ax.tick_params(axis="x", pad=14)
+for label, raw_angle in zip(tick_labels, angles[:-1], strict=True):
+    cos_disp = np.cos(np.pi / 2 - raw_angle)
+    if cos_disp > 0.3:
+        label.set_horizontalalignment("left")
+    elif cos_disp < -0.3:
+        label.set_horizontalalignment("right")
+    else:
+        label.set_horizontalalignment("center")
+
+# Set radial grid — fewer labels (25/50/75/100) placed in the empty sector
+# between Display and Build Quality, away from every category axis, so they
+# no longer collide with each other or with the data. Labels keep an opaque
+# halo so they stay legible where polygon fills cross the radial axis
 ax.set_ylim(0, 100)
-ax.set_yticks([20, 40, 60, 80, 100])
-ax.set_yticklabels(["20", "40", "60", "80", "100"], fontsize=16, color=INK_SOFT)
+ax.set_yticks([25, 50, 75, 100])
+r_tick_labels = ax.set_yticklabels(["25", "50", "75", "100"], fontsize=13, color=INK_SOFT)
+# set_rlabel_position takes a RAW (pre-rotation) angle; raw=210 (Build
+# Quality's own axis) renders at display angle 240 = between Display (270)
+# and Build Quality (210) after the theta_zero_location/direction rotation
+ax.set_rlabel_position(210)
+for label in r_tick_labels:
+    label.set_bbox({"facecolor": PAGE_BG, "edgecolor": "none", "alpha": 0.9, "pad": 1.5})
 
 # Grid styling
 ax.yaxis.grid(True, linestyle="-", alpha=0.15, linewidth=0.8, color=INK_SOFT)
 ax.xaxis.grid(True, linestyle="-", alpha=0.15, linewidth=0.8, color=INK_SOFT)
 
-# Title
-ax.set_title("radar-multi · matplotlib · anyplot.ai", fontsize=24, fontweight="medium", color=INK, pad=40)
+# Title — figure-level (not axes-level) so it stays centered on the full
+# canvas regardless of how the legend reshapes the polar axes below
+fig.suptitle("radar-multi · python · matplotlib · anyplot.ai", fontsize=12, fontweight="medium", color=INK, y=0.97)
 
-# Legend
-leg = ax.legend(loc="upper left", bbox_to_anchor=(1.05, 1.0), fontsize=16, framealpha=1.0)
+# Legend outside the circular grid, vertically centered — leader label
+# rendered bold to echo its bolder polygon
+leg = ax.legend(loc="center left", bbox_to_anchor=(1.08, 0.5), fontsize=13, framealpha=1.0)
 leg.get_frame().set_facecolor(ELEVATED_BG)
 leg.get_frame().set_edgecolor(INK_SOFT)
 leg.get_frame().set_linewidth(0.8)
-for text in leg.get_texts():
+for idx, text in enumerate(leg.get_texts()):
     text.set_color(INK)
-
-plt.tight_layout()
-plt.savefig(f"plot-{THEME}.png", dpi=300, bbox_inches="tight", facecolor=PAGE_BG)
+    if idx == leader_idx:
+        text.set_fontweight("bold")
+
+# Explicit margins (not tight_layout) so the polar axes sit vertically
+# centered in the square canvas — top/bottom margins balanced, right margin
+# reserved for the legend
+fig.subplots_adjust(left=0.32, right=0.66, top=0.80, bottom=0.20)
+plt.savefig(f"plot-{THEME}.png", dpi=400, facecolor=PAGE_BG)