Circle Packing

import pandas as pd
import matplotlib.pyplot as plt
import matplotlib.patches as patches
import matplotlib.colors as mcolors
import matplotlib.cm as cm
import circlify

# === 1. DATA ===
df = pd.DataFrame({
    'Department': ['Marketing', 'Marketing', 'Engineering', 'Engineering', 'Sales', 'Sales', 'HR', 'HR'],
    'Subcategory': ['Advertising', 'Social Media', 'Development', 'Testing', 'Direct Sales', 'Online Sales', 'Recruitment', 'Training'],
    'Budget': [30000000, 20000000, 50000000, 15000000, 25000000, 18000000, 12000000, 8000000]
})

# === 2. HIERARCHY BUILDING ===
data = []
for dept, group in df.groupby('Department'):
    sub_children = []
    for _, row in group.iterrows():
        sub_children.append({'id': row['Subcategory'], 'datum': row['Budget']})
    data.append({'id': dept, 'datum': group['Budget'].sum(), 'children': sub_children})

# Compute circle positions (always normalized to radius 1.0)
circles = circlify.circlify(
    data, 
    show_enclosure=False, 
    target_enclosure=circlify.Circle(x=0, y=0, r=1)
)

# === 3. SETUP PLOT (THE FIX) ===
fig, ax = plt.subplots(figsize=(14, 14), facecolor='white')

# !!! CRITICAL FIX: Lock the view to see the whole unit circle !!!
ax.set_xlim(-1.2, 1.2)
ax.set_ylim(-1.2, 1.2)
ax.axis('off')
ax.set_aspect('equal') # Prevents distortion

# Colormap setup
budgets = df['Budget'].values
norm = mcolors.LogNorm(vmin=min(budgets), vmax=max(budgets))
cmap = cm.get_cmap('magma_r')

# === 4. DRAWING LOOP ===
for circle in circles:
    x, y, r = circle.x, circle.y, circle.r
    level = circle.level
    
    if level == 1:
        # --- PARENT (Department) ---
        # Draw a light container circle
        ax.add_patch(patches.Circle(
            (x, y), r, 
            facecolor='#f0f0f0', 
            edgecolor='#999999', 
            linewidth=2,
            zorder=0  # BACKGROUND LAYER
        ))
        
        # Label: Place at the top edge of the circle
        label_y = y + r 
        ax.text(
            x, label_y, 
            circle.ex['id'].upper(), 
            ha='center', va='bottom', 
            fontsize=16, fontweight='bold', color='#333333',
            zorder=2
        )

    elif level == 2:
        # --- CHILD (Subcategory) ---
        budget = circle.ex['datum']
        label = circle.ex['id']
        
        # Color based on budget
        color = cmap(norm(budget))
        
        # Draw the bubble
        ax.add_patch(patches.Circle(
            (x, y), r * 0.95, # Slight gap
            facecolor=color, 
            edgecolor='white', 
            linewidth=1,
            zorder=1 # FOREGROUND LAYER
        ))
        
        # Smart Labeling (Hide if too small)
        if r > 0.05:
            # Contrast check
            lum = 0.2126*color[0] + 0.7152*color[1] + 0.0722*color[2]
            text_col = 'black' if lum > 0.6 else 'white'
            
            # Label
            ax.text(x, y + r*0.15, label, ha='center', va='center', 
                    fontsize=11, fontweight='bold', color=text_col, zorder=3)
            # Value
            val_str = f"${budget/1000000:.1f}M"
            ax.text(x, y - r*0.15, val_str, ha='center', va='center', 
                    fontsize=9, color=text_col, zorder=3)

# === 5. TITLE & LEGEND ===
total_budget = df['Budget'].sum()
plt.title(f"Budget Allocation (Total: ${total_budget/1000000:.1f}M)", 
          fontsize=24, fontweight='bold', y=0.95)

# Add Colorbar
sm = plt.cm.ScalarMappable(cmap=cmap, norm=norm)
sm.set_array([])
cbar = plt.colorbar(sm, ax=ax, shrink=0.5, pad=0.02)
cbar.set_label('Budget Scale (Log)', fontsize=12)

plt.tight_layout()
plt.savefig('fixed_budget_plot.png', dpi=300)
plt.show()