Pie Charts & Subplots in Matplotlib — Baby Steps

Keyword: matplotlib pie chart • Difficulty: Beginner • Author: Champak Roy

Pie charts display how data categories relate to a whole. Subplots help you compare multiple pies side by side. This example runs directly in your browser using Pyodide — a full Python environment in WebAssembly.

Examples

labels = ['A','B','C']; sizes = [30,45,25]
plt.pie(sizes, labels=labels, autopct='%1.1f%%'); plt.axis('equal')

fig, axes = plt.subplots(1,2,figsize=(8,4))
axes[0].pie(sizes,...)
axes[1].pie(other_sizes,...)
plt.tight_layout()

🧪 Practice: Run Matplotlib with Pyodide

Click Preload Pyodide to prepare the environment. Then edit the Python code and click Run & Render to see the chart below.

# Robust Pie Charts + Subplots (returns OK:<b64> or ERR:<traceback>)
import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
import io, base64, traceback

try:
    labels = ['Direct','Referral','Social']
    sizes = [30,45,25]
    colors = ['#66c2a5','#fc8d62','#8da0cb']

labels2 = ['Desktop','Mobile','Tablet']
    sizes2 = [40,35,25]
    colors2 = ['#97d6c7','#ffd166','#a0c4ff']
    explode = (0,0.08,0)

fig, axes = plt.subplots(1,2,figsize=(9,4))
    axes[0].pie(sizes, labels=labels, autopct='%1.0f%%', startangle=90,
                explode=explode, colors=colors, wedgeprops={'edgecolor':'white'})
    axes[0].set_title('Traffic Sources')
    axes[0].axis('equal')

wedges, texts, autotexts = axes[1].pie(sizes2, labels=labels2, autopct='%1.0f%%',
                                          startangle=140, colors=colors2, wedgeprops={'edgecolor':'white'})
    centre = plt.Circle((0,0),0.55,color='white')
    axes[1].add_artist(centre)
    axes[1].set_title('Device Share')
    axes[1].axis('equal')
    plt.tight_layout()

buf = io.BytesIO()
    fig.savefig(buf, format='png', bbox_inches='tight')
    plt.close(fig)
    buf.seek(0)
    'OK:' + base64.b64encode(buf.read()).decode('ascii')
except Exception:
    'ERR:' + traceback.format_exc()

Idle

Console / stderr:

Rendered Chart

No chart yet — run code to render a PNG here.