feat(bokeh): implement polar-bar (#2759)

## Implementation: `polar-bar` - bokeh

Implements the **bokeh** version of `polar-bar`.

**File:** `plots/polar-bar/implementations/bokeh.py`

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/20601057120)*

---------

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

Author: github-actions[bot]

plots/polar-bar/implementations/bokeh.py

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+""" pyplots.ai
+polar-bar: Polar Bar Chart (Wind Rose)
+Library: bokeh 3.8.1 | Python 3.13.11
+Quality: 92/100 | Created: 2025-12-30
+"""
+
+import numpy as np
+from bokeh.io import export_png
+from bokeh.models import ColumnDataSource, Label, Title
+from bokeh.palettes import Blues8
+from bokeh.plotting import figure
+
+
+# Data - Wind frequency by direction (8 compass points)
+np.random.seed(42)
+directions = ["N", "NE", "E", "SE", "S", "SW", "W", "NW"]
+# Simulating wind pattern: prevailing winds from SW and W
+frequencies = np.array([12, 8, 10, 6, 9, 18, 22, 14])
+
+# Convert directions to angles (0° = North, clockwise)
+# In Bokeh, angles are counterclockwise from East, so we need to convert
+n_dirs = len(directions)
+angles = np.linspace(0, 2 * np.pi, n_dirs, endpoint=False)
+# Bokeh: 0 = East, pi/2 = North, counterclockwise
+start_angles = np.pi / 2 - angles - np.pi / n_dirs
+end_angles = np.pi / 2 - angles + np.pi / n_dirs
+
+# Normalize frequencies for bar length
+max_freq = frequencies.max()
+radii = frequencies / max_freq * 0.75  # Scale to 75% of plot radius
+
+# Colors - Python Blue palette
+colors = [Blues8[min(7, max(0, 7 - int((f / max_freq) * 7)))] for f in frequencies]
+
+# Create figure (square for polar plot)
+p = figure(width=3600, height=3600, x_range=(-1.05, 1.05), y_range=(-1.05, 1.05), tools="", toolbar_location=None)
+
+# Remove axes and grid for polar appearance
+p.axis.visible = False
+p.grid.visible = False
+p.outline_line_color = None
+p.background_fill_color = "#fafafa"
+
+# Title styling
+p.title = Title(text="polar-bar · bokeh · pyplots.ai", text_font_size="42pt", text_color="#306998", align="center")
+
+# Draw concentric reference circles
+circle_radii = [0.25, 0.50, 0.75]
+for r in circle_radii:
+    p.circle(x=0, y=0, radius=r, fill_color=None, line_color="#aaaaaa", line_width=2, line_dash="dashed")
+
+# Draw outer circle
+p.circle(x=0, y=0, radius=0.85, fill_color=None, line_color="#888888", line_width=2)
+
+# Draw radial lines for each direction
+for i in range(n_dirs):
+    angle = np.pi / 2 - angles[i]
+    x_end = np.cos(angle) * 0.85
+    y_end = np.sin(angle) * 0.85
+    p.line([0, x_end], [0, y_end], line_color="#cccccc", line_width=1.5)
+
+# Draw wedges (polar bars)
+source = ColumnDataSource(
+    data={
+        "x": [0] * n_dirs,
+        "y": [0] * n_dirs,
+        "radius": radii.tolist(),
+        "start_angle": start_angles.tolist(),
+        "end_angle": end_angles.tolist(),
+        "color": colors,
+        "direction": directions,
+        "frequency": frequencies.tolist(),
+    }
+)
+
+p.wedge(
+    x="x",
+    y="y",
+    radius="radius",
+    start_angle="start_angle",
+    end_angle="end_angle",
+    fill_color="color",
+    fill_alpha=0.9,
+    line_color="#306998",
+    line_width=3,
+    source=source,
+)
+
+# Add direction labels around the plot
+label_radius = 0.93
+for i, direction in enumerate(directions):
+    angle = np.pi / 2 - angles[i]
+    x_label = np.cos(angle) * label_radius
+    y_label = np.sin(angle) * label_radius
+
+    label = Label(
+        x=x_label,
+        y=y_label,
+        text=direction,
+        text_font_size="32pt",
+        text_font_style="bold",
+        text_color="#306998",
+        text_align="center",
+        text_baseline="middle",
+    )
+    p.add_layout(label)
+
+# Add frequency scale labels at reference circles
+for r in circle_radii:
+    freq_val = int(r / 0.75 * max_freq)
+    label = Label(
+        x=0.03,
+        y=r + 0.015,
+        text=f"{freq_val}%",
+        text_font_size="20pt",
+        text_color="#666666",
+        text_align="left",
+        text_baseline="bottom",
+    )
+    p.add_layout(label)
+
+# Save as PNG
+export_png(p, filename="plot.png")

plots/polar-bar/metadata/bokeh.yaml

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+library: bokeh
+specification_id: polar-bar
+created: '2025-12-30T16:30:56Z'
+updated: '2025-12-30T16:39:50Z'
+generated_by: claude-opus-4-5-20251101
+workflow_run: 20601057120
+issue: 0
+python_version: 3.13.11
+library_version: 3.8.1
+preview_url: https://storage.googleapis.com/pyplots-images/plots/polar-bar/bokeh/plot.png
+preview_thumb: https://storage.googleapis.com/pyplots-images/plots/polar-bar/bokeh/plot_thumb.png
+preview_html: https://storage.googleapis.com/pyplots-images/plots/polar-bar/bokeh/plot.html
+quality_score: 92
+review:
+  strengths:
+  - Excellent use of Bokeh wedge glyph to create authentic polar bars
+  - Clean mathematical transformation from compass directions to Bokeh angle system
+  - Professional styling with Python blue (#306998) color scheme throughout
+  - Good use of ColumnDataSource for data organization
+  - Reference circles and radial lines provide clear visual guides
+  - Color intensity mapping to frequency adds extra visual dimension
+  weaknesses:
+  - Scale labels show percent symbol but data represents raw frequency counts, which
+    is semantically inconsistent
+  - No legend or annotation explaining what the colors and values represent