Matplotlib-In-Python-Bar-Charts

Bar Charts in Matplotlib — Baby Steps

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

Bar charts are simple, powerful, and everywhere — from marksheets to stock charts. Let’s learn them step-by-step with clear examples, and you can even run the code live below using Python (Pyodide)!

💡 Step-by-Step Tutorial

1) Import Matplotlib

import matplotlib.pyplot as plt

2) Prepare your data

languages = ['Python', 'Java', 'C', 'C++', 'JavaScript']
students = [80, 65, 50, 40, 70]

3) Draw your first bar chart

plt.bar(languages, students)
plt.show()

4) Add colors and labels

plt.bar(languages, students, color='skyblue', edgecolor='navy')
plt.title("Programming Language Popularity")
plt.xlabel("Languages")
plt.ylabel("Number of Students")
plt.show()

5) Horizontal bars

plt.barh(languages, students, color='lightgreen')
plt.xlabel("Number of Students")
plt.show()

6) Add numbers on top

plt.bar(languages, students, color='#69b3a2')
for i, v in enumerate(students):
    plt.text(i, v + 1, str(v), ha='center')
plt.show()

💬 Tip: In the Pyodide practice section below, use matplotlib.use('Agg') and save your figure with plt.savefig() to display it.

📊 Sample static output:

🧪 Practice: Run Matplotlib with Pyodide

Click Preload Pyodide once to install matplotlib and numpy. Then press Run & Render to display your chart as an image!

# Example: simple bar chart using Pyodide import matplotlib matplotlib.use('Agg') import matplotlib.pyplot as plt import io, base64 langs = ['Python','Java','C','C++','JavaScript'] vals = [80,65,50,40,70] plt.figure(figsize=(6,3)) bars = plt.bar(langs, vals, color='#69b3a2', edgecolor='navy') plt.title('Programming Language Popularity') plt.xlabel('Language') plt.ylabel('Students') for bar in bars: h = bar.get_height() plt.text(bar.get_x()+bar.get_width()/2, h+1, str(int(h)), ha='center') buf = io.BytesIO() plt.tight_layout() plt.savefig(buf, format='png') buf.seek(0) base64.b64encode(buf.read()).decode('ascii')

Idle

Console output:

Rendered Chart

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

🧠 Tips & Notes

• Always call matplotlib.use('Agg') when plotting in Pyodide.
• Pyodide runs in your browser, so it can be slow on the first load.
• If the code doesn’t run, try refreshing and clicking “Preload Pyodide” again.

© Learning Sutras — Champak Roy | Made with 💙 in Varanasi