feat(letsplot): implement icicle-basic (#2541)

## Implementation: `icicle-basic` - letsplot

Implements the **letsplot** version of `icicle-basic`.

**File:** `plots/icicle-basic/implementations/letsplot.py`

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/20585402234)*

---------

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/icicle-basic/implementations/letsplot.py

@@ -0,0 +1,176 @@
+""" pyplots.ai
+icicle-basic: Basic Icicle Chart
+Library: letsplot 4.8.2 | Python 3.13.11
+Quality: 90/100 | Created: 2025-12-30
+"""
+
+import pandas as pd
+from lets_plot import (
+    LetsPlot,
+    aes,
+    element_blank,
+    element_text,
+    geom_rect,
+    geom_text,
+    ggplot,
+    ggsave,
+    ggsize,
+    labs,
+    scale_fill_manual,
+    scale_size_identity,
+    theme,
+    xlim,
+    ylim,
+)
+
+
+LetsPlot.setup_html()
+
+# Hierarchical data: File system example
+# Structure: Root -> Folders -> Subfolders/Files
+hierarchy = [
+    # Level 0: Root
+    {"name": "root", "parent": "", "value": 1000},
+    # Level 1: Main folders
+    {"name": "Documents", "parent": "root", "value": 350},
+    {"name": "Media", "parent": "root", "value": 400},
+    {"name": "Projects", "parent": "root", "value": 250},
+    # Level 2: Subfolders
+    {"name": "Work", "parent": "Documents", "value": 200},
+    {"name": "Personal", "parent": "Documents", "value": 150},
+    {"name": "Photos", "parent": "Media", "value": 220},
+    {"name": "Videos", "parent": "Media", "value": 180},
+    {"name": "Python", "parent": "Projects", "value": 120},
+    {"name": "Web", "parent": "Projects", "value": 130},
+    # Level 3: Files/items
+    {"name": "Reports", "parent": "Work", "value": 120},
+    {"name": "Contracts", "parent": "Work", "value": 80},
+    {"name": "Letters", "parent": "Personal", "value": 90},
+    {"name": "Receipts", "parent": "Personal", "value": 60},
+    {"name": "2024", "parent": "Photos", "value": 130},
+    {"name": "2023", "parent": "Photos", "value": 90},
+    {"name": "Movies", "parent": "Videos", "value": 100},
+    {"name": "Clips", "parent": "Videos", "value": 80},
+    {"name": "DataViz", "parent": "Python", "value": 70},
+    {"name": "ML", "parent": "Python", "value": 50},
+    {"name": "Frontend", "parent": "Web", "value": 75},
+    {"name": "Backend", "parent": "Web", "value": 55},
+]
+
+# Build tree structure
+name_to_node = {row["name"]: row for row in hierarchy}
+children = {}
+for row in hierarchy:
+    parent = row["parent"]
+    if parent not in children:
+        children[parent] = []
+    if parent:
+        children[parent].append(row["name"])
+
+# Calculate level for each node (using iteration instead of function)
+levels = {}
+for row in hierarchy:
+    level = 0
+    current = row["name"]
+    while name_to_node[current]["parent"]:
+        level += 1
+        current = name_to_node[current]["parent"]
+    levels[row["name"]] = level
+
+max_level = max(levels.values())
+
+# Calculate rectangle positions (horizontal icicle: root at top)
+# Using stack-based traversal instead of recursion
+rects = []
+stack = [("root", 0.0, 1.0)]
+
+while stack:
+    name, x_start, x_end = stack.pop()
+    level = levels[name]
+
+    # Add rectangle for this node
+    rects.append(
+        {
+            "name": name,
+            "xmin": x_start,
+            "xmax": x_end,
+            "ymin": max_level - level,
+            "ymax": max_level - level + 1,
+            "level": level,
+        }
+    )
+
+    # Process children (add in reverse order so first child is processed first)
+    if name in children and children[name]:
+        child_names = children[name]
+        total_value = sum(name_to_node[c]["value"] for c in child_names)
+        current_x = x_start
+
+        for child_name in reversed(child_names):
+            child_value = name_to_node[child_name]["value"]
+            child_width = (x_end - x_start) * (child_value / total_value)
+            # Calculate position for this child
+            child_x_start = x_end - child_width
+            stack.append((child_name, child_x_start, x_end))
+            x_end = child_x_start
+
+# Create dataframe for rectangles
+rect_df = pd.DataFrame(rects)
+rect_df["level_str"] = rect_df["level"].astype(str)
+
+# Calculate center positions for labels
+rect_df["x_center"] = (rect_df["xmin"] + rect_df["xmax"]) / 2
+rect_df["y_center"] = (rect_df["ymin"] + rect_df["ymax"]) / 2
+rect_df["width"] = rect_df["xmax"] - rect_df["xmin"]
+
+# Only show labels for rectangles wide enough (threshold based on label length)
+# Balanced threshold to show labels while avoiding overlap
+rect_df["label_len"] = rect_df["name"].str.len()
+rect_df["show_label"] = rect_df["width"] > (rect_df["label_len"] * 0.007 + 0.01)
+label_df = rect_df[rect_df["show_label"]].copy()
+
+# Adjust font size based on level for better fit (smaller at deeper levels to prevent overlap)
+label_df["font_size"] = label_df["level"].map({0: 14, 1: 12, 2: 8, 3: 7})
+
+# Color palette by level (Python colors + complementary)
+colors = {
+    "0": "#306998",  # Python Blue - root
+    "1": "#FFD43B",  # Python Yellow - level 1
+    "2": "#4B8BBE",  # Light blue - level 2
+    "3": "#646464",  # Gray - level 3
+}
+
+# Create plot
+plot = (
+    ggplot()
+    + geom_rect(
+        aes(xmin="xmin", xmax="xmax", ymin="ymin", ymax="ymax", fill="level_str"),
+        data=rect_df,
+        color="white",
+        size=1.5,
+        alpha=0.9,
+    )
+    + geom_text(
+        aes(x="x_center", y="y_center", label="name", size="font_size"), data=label_df, color="black", fontface="bold"
+    )
+    + scale_fill_manual(values=colors, name="Level")
+    + scale_size_identity()
+    + xlim(-0.02, 1.02)
+    + ylim(-0.1, max_level + 1.1)
+    + labs(title="icicle-basic · letsplot · pyplots.ai")
+    + theme(
+        axis_title=element_blank(),
+        axis_text=element_blank(),
+        axis_ticks=element_blank(),
+        axis_line=element_blank(),
+        panel_grid=element_blank(),
+        plot_title=element_text(size=24, face="bold"),
+        legend_text=element_text(size=16),
+        legend_title=element_text(size=18),
+    )
+    + ggsize(1600, 900)
+)
+
+# Save as PNG (scale 3x for 4800x2700) and HTML in current directory
+ggsave(plot, "plot.png", path=".", scale=3)
+ggsave(plot, "plot.html", path=".")

plots/icicle-basic/metadata/letsplot.yaml

@@ -0,0 +1,28 @@
+library: letsplot
+specification_id: icicle-basic
+created: '2025-12-30T00:07:18Z'
+updated: '2025-12-30T00:29:53Z'
+generated_by: claude-opus-4-5-20251101
+workflow_run: 20585402234
+issue: 0
+python_version: 3.13.11
+library_version: 4.8.2
+preview_url: https://storage.googleapis.com/pyplots-images/plots/icicle-basic/letsplot/plot.png
+preview_thumb: https://storage.googleapis.com/pyplots-images/plots/icicle-basic/letsplot/plot_thumb.png
+preview_html: https://storage.googleapis.com/pyplots-images/plots/icicle-basic/letsplot/plot.html
+quality_score: 90
+review:
+  strengths:
+  - Clean hierarchical visualization with clear parent-child relationships through
+    spatial adjacency
+  - Intelligent label visibility logic that hides labels for narrow rectangles to
+    prevent overlap
+  - Good color scheme with Python-themed colors (blue/yellow) that are colorblind-safe
+  - Proper horizontal orientation with root at top as specified
+  - Well-structured code using stack-based traversal instead of recursion
+  weaknesses:
+  - Legend could be more descriptive (e.g., "Hierarchy Level" instead of just "Level")
+  - Some empty space at the bottom of the canvas could be better utilized
+  - Several level 3 labels are hidden (Reports, Contracts, Letters, Receipts, 2024,
+    2023, Movies, DataViz, Frontend, Backend) - while this prevents overlap, it reduces
+    information density