feat(plotly): implement pie-drilldown (#3121)

## Implementation: `pie-drilldown` - plotly

Implements the **plotly** version of `pie-drilldown`.

**File:** `plots/pie-drilldown/implementations/plotly.py`

**Parent Issue:** #3072

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/20620475114)*

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

plots/pie-drilldown/implementations/plotly.py

@@ -0,0 +1,255 @@
+""" pyplots.ai
+pie-drilldown: Drilldown Pie Chart with Click Navigation
+Library: plotly 6.5.0 | Python 3.13.11
+Quality: 91/100 | Created: 2025-12-31
+"""
+
+import json
+
+import plotly.graph_objects as go
+
+
+# Hierarchical data structure for company budget breakdown
+# Structure: Department -> Team -> Expense Category
+# Leaf nodes have direct values, parent nodes derive values from children
+hierarchy = {
+    "All": {"children": ["Engineering", "Marketing", "Operations", "Sales"], "parent": None},
+    "Engineering": {"children": ["Backend", "Frontend", "DevOps", "QA"], "parent": "All"},
+    "Marketing": {"children": ["Digital", "Content", "Events", "Brand"], "parent": "All"},
+    "Operations": {"children": ["HR", "Finance", "Legal", "Facilities"], "parent": "All"},
+    "Sales": {"children": ["Enterprise", "SMB", "Partnerships"], "parent": "All"},
+    # Engineering subcategories (leaf nodes with values)
+    "Backend": {"value": 850000, "parent": "Engineering"},
+    "Frontend": {"value": 620000, "parent": "Engineering"},
+    "DevOps": {"value": 480000, "parent": "Engineering"},
+    "QA": {"value": 350000, "parent": "Engineering"},
+    # Marketing subcategories
+    "Digital": {"value": 420000, "parent": "Marketing"},
+    "Content": {"value": 280000, "parent": "Marketing"},
+    "Events": {"value": 350000, "parent": "Marketing"},
+    "Brand": {"value": 180000, "parent": "Marketing"},
+    # Operations subcategories
+    "HR": {"value": 320000, "parent": "Operations"},
+    "Finance": {"value": 290000, "parent": "Operations"},
+    "Legal": {"value": 410000, "parent": "Operations"},
+    "Facilities": {"value": 250000, "parent": "Operations"},
+    # Sales subcategories
+    "Enterprise": {"value": 680000, "parent": "Sales"},
+    "SMB": {"value": 420000, "parent": "Sales"},
+    "Partnerships": {"value": 300000, "parent": "Sales"},
+}
+
+# Pre-compute parent values (sum of children)
+hierarchy["Engineering"]["value"] = sum(hierarchy[c]["value"] for c in hierarchy["Engineering"]["children"])
+hierarchy["Marketing"]["value"] = sum(hierarchy[c]["value"] for c in hierarchy["Marketing"]["children"])
+hierarchy["Operations"]["value"] = sum(hierarchy[c]["value"] for c in hierarchy["Operations"]["children"])
+hierarchy["Sales"]["value"] = sum(hierarchy[c]["value"] for c in hierarchy["Sales"]["children"])
+
+# Color palette for main categories (colorblind-safe, distinct hues)
+colors = {
+    "Engineering": "#306998",  # Blue
+    "Marketing": "#9467BD",  # Purple (changed from yellow for better distinction)
+    "Operations": "#2CA02C",  # Green
+    "Sales": "#E24A33",  # Red-orange (changed from orange for better distinction)
+}
+
+# Lighter shades for subcategories (matching parent color families)
+sub_colors = {
+    # Engineering - Blue shades
+    "Backend": "#4A8BBE",
+    "Frontend": "#6BA3D6",
+    "DevOps": "#8CBBEE",
+    "QA": "#ADD3F5",
+    # Marketing - Purple shades
+    "Digital": "#A87ACC",
+    "Content": "#BB94DB",
+    "Events": "#CEAEEA",
+    "Brand": "#E1C8F9",
+    # Operations - Green shades
+    "HR": "#4DC04D",
+    "Finance": "#70D070",
+    "Legal": "#93E093",
+    "Facilities": "#B6F0B6",
+    # Sales - Red-orange shades
+    "Enterprise": "#E86F5C",
+    "SMB": "#F09485",
+    "Partnerships": "#F7B9AE",
+}
+
+# Get data for top level view
+current_level = "All"
+children = hierarchy[current_level]["children"]
+values = [hierarchy[child]["value"] for child in children]
+total = sum(values)
+slice_colors = [colors[child] for child in children]
+
+# Create pie chart
+fig = go.Figure()
+
+# Main pie chart with sort=False to preserve order (legend matches clockwise visual order)
+fig.add_trace(
+    go.Pie(
+        labels=children,
+        values=values,
+        hole=0.3,  # Donut style for modern look
+        textinfo="label+percent",
+        textposition="outside",
+        textfont={"size": 20},
+        hovertemplate="<b>%{label}</b><br>"
+        + "Value: $%{value:,.0f}<br>"
+        + "Percentage: %{percent}<br>"
+        + "<extra>Click to drill down</extra>",
+        marker={"colors": slice_colors, "line": {"color": "white", "width": 3}},
+        pull=[0.02] * len(children),  # Slight separation
+        sort=False,  # Preserve data order so legend matches clockwise visual order
+    )
+)
+
+# Add center text showing current view
+fig.add_annotation(
+    text="<b>Company Budget</b><br>FY 2024",
+    x=0.5,
+    y=0.5,
+    font={"size": 24, "color": "#333333"},
+    showarrow=False,
+    xref="paper",
+    yref="paper",
+)
+
+# Add breadcrumb navigation at the top
+fig.add_annotation(
+    text="📍 All Departments",
+    x=0.02,
+    y=0.98,
+    xanchor="left",
+    yanchor="top",
+    font={"size": 22, "color": "#306998"},
+    showarrow=False,
+    xref="paper",
+    yref="paper",
+    bgcolor="rgba(255,255,255,0.9)",
+    borderpad=8,
+)
+
+# Add click instruction
+fig.add_annotation(
+    text="👆 Click any slice to drill down into subcategories",
+    x=0.5,
+    y=0.02,
+    xanchor="center",
+    yanchor="bottom",
+    font={"size": 18, "color": "#666666"},
+    showarrow=False,
+    xref="paper",
+    yref="paper",
+)
+
+# Update layout
+fig.update_layout(
+    title={
+        "text": "pie-drilldown · plotly · pyplots.ai",
+        "font": {"size": 28, "color": "#333333"},
+        "x": 0.5,
+        "xanchor": "center",
+    },
+    showlegend=True,
+    legend={
+        "orientation": "v",
+        "yanchor": "middle",
+        "y": 0.5,
+        "xanchor": "left",
+        "x": 1.02,
+        "font": {"size": 18},
+        "title": {"text": "Departments", "font": {"size": 20}},
+    },
+    template="plotly_white",
+    margin={"l": 60, "r": 200, "t": 100, "b": 80},
+)
+
+# Custom JavaScript for drilldown functionality (in HTML output)
+# Uses json.dumps for robust serialization (no fragile string replacement)
+hierarchy_json = json.dumps(hierarchy)
+colors_json = json.dumps(colors)
+sub_colors_json = json.dumps(sub_colors)
+
+drilldown_js = f"""
+<script>
+var hierarchyData = {hierarchy_json};
+var colors = {colors_json};
+var subColors = {sub_colors_json};
+var currentPath = ['All'];
+
+function getValue(nodeName) {{
+    return hierarchyData[nodeName].value;
+}}
+
+function updateBreadcrumb() {{
+    var breadcrumb = '📍 ' + currentPath.join(' > ');
+    var annotations = document.querySelectorAll('.annotation-text');
+    annotations.forEach(function(el) {{
+        if (el.textContent.startsWith('📍')) {{
+            el.textContent = breadcrumb;
+        }}
+    }});
+}}
+
+function updateChart(level) {{
+    var node = hierarchyData[level];
+    if (!node.children) return;
+
+    var children = node.children;
+    var values = children.map(c => getValue(c));
+    var sliceColors = children.map(c => subColors[c] || colors[c] || '#306998');
+
+    Plotly.animate('plotly-chart', {{
+        data: [{{
+            labels: children,
+            values: values,
+            marker: {{colors: sliceColors}}
+        }}],
+        layout: {{}}
+    }}, {{
+        transition: {{duration: 500, easing: 'cubic-in-out'}},
+        frame: {{duration: 500}}
+    }});
+    updateBreadcrumb();
+}}
+
+document.getElementById('plotly-chart').on('plotly_click', function(data) {{
+    var clickedLabel = data.points[0].label;
+    if (hierarchyData[clickedLabel] && hierarchyData[clickedLabel].children) {{
+        currentPath.push(clickedLabel);
+        updateChart(clickedLabel);
+    }}
+}});
+
+// Double-click to go back up the hierarchy
+document.getElementById('plotly-chart').on('plotly_doubleclick', function() {{
+    if (currentPath.length > 1) {{
+        currentPath.pop();
+        updateChart(currentPath[currentPath.length - 1]);
+    }}
+}});
+</script>
+"""
+
+# Save as PNG (static image for main output)
+fig.write_image("plot.png", width=1600, height=900, scale=3)
+
+# Save as HTML (interactive version with drilldown)
+html_content = fig.to_html(
+    full_html=True,
+    include_plotlyjs=True,
+    div_id="plotly-chart",
+    config={
+        "displayModeBar": True,
+        "modeBarButtonsToRemove": ["lasso2d", "select2d"],
+        "toImageButtonOptions": {"format": "png", "width": 4800, "height": 2700},
+    },
+)
+
+# Inject drilldown JavaScript before closing body tag
+html_content = html_content.replace("</body>", drilldown_js + "</body>")
+
+with open("plot.html", "w") as f:
+    f.write(html_content)

plots/pie-drilldown/metadata/plotly.yaml

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+library: plotly
+specification_id: pie-drilldown
+created: '2025-12-31T14:04:59Z'
+updated: '2025-12-31T14:26:12Z'
+generated_by: claude-opus-4-5-20251101
+workflow_run: 20620475114
+issue: 3072
+python_version: 3.13.11
+library_version: 6.5.0
+preview_url: https://storage.googleapis.com/pyplots-images/plots/pie-drilldown/plotly/plot.png
+preview_thumb: https://storage.googleapis.com/pyplots-images/plots/pie-drilldown/plotly/plot_thumb.png
+preview_html: https://storage.googleapis.com/pyplots-images/plots/pie-drilldown/plotly/plot.html
+quality_score: 91
+review:
+  strengths:
+  - Excellent use of Plotly interactive capabilities with custom JavaScript for drilldown
+    navigation
+  - Professional colorblind-safe color scheme with consistent subcategory shades
+  - Robust JSON serialization for data passing to JavaScript (no fragile string replacement)
+  - Clear breadcrumb navigation and user instructions
+  - Clean donut style with center annotation adds modern aesthetic
+  - Dual output (PNG + HTML) maximizes utility
+  weaknesses:
+  - Minor text overlap between breadcrumb annotation and Marketing slice label in
+    top-left area
+  - Static PNG cannot demonstrate the drilldown functionality - consider adjusting
+    breadcrumb position to avoid overlap