How to add text inside a plot in Matplotlib?

Adding text inside a plot in Matplotlib allows you to annotate charts with labels, equations, or explanatory notes. You can use the text() function to place text at specific coordinates with customizable styling.

Basic Text Placement

The plt.text() function takes x and y coordinates along with the text string ?

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(0, 10, 100)
y = np.sin(x)

plt.figure(figsize=(8, 5))
plt.plot(x, y, 'b-', linewidth=2)
plt.text(5, 0.5, 'Sine Wave', fontsize=14, color='red')
plt.title('Basic Text Example')
plt.grid(True, alpha=0.3)
plt.show()

Text with Mathematical Expressions

Use LaTeX syntax within dollar signs for mathematical formulas ?

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-5, 5, 100)
y = x ** 3

plt.figure(figsize=(8, 6))
plt.plot(x, y, 'g-', linewidth=2)
plt.text(0, 50, r'$y = x^3$', fontsize=20, 
         bbox=dict(facecolor='yellow', alpha=0.7, pad=10))
plt.text(-3, -80, r'$\frac{dy}{dx} = 3x^2$', fontsize=16, 
         bbox=dict(facecolor='lightblue', alpha=0.7))
plt.title('Mathematical Expressions in Text')
plt.grid(True, alpha=0.3)
plt.show()

Text Styling and Positioning

Control text appearance with font properties, colors, and background boxes ?

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(0, 2*np.pi, 100)
y1 = np.sin(x)
y2 = np.cos(x)

plt.figure(figsize=(10, 6))
plt.plot(x, y1, 'b-', label='sin(x)')
plt.plot(x, y2, 'r-', label='cos(x)')

# Different text styling examples
plt.text(1, 0.8, 'Maximum', fontsize=12, weight='bold', 
         ha='center', va='bottom', color='blue')
plt.text(4.5, -0.8, 'Minimum', fontsize=12, style='italic',
         ha='center', va='top', color='red')
plt.text(3, 0.5, 'Intersection\nPoint', fontsize=10,
         bbox=dict(boxstyle='round,pad=0.5', facecolor='wheat', alpha=0.8),
         ha='center', va='center')

plt.title('Styled Text Examples')
plt.legend()
plt.grid(True, alpha=0.3)
plt.show()

Text Positioning Options

Multiple Text Elements

Add multiple text annotations to highlight different parts of your plot ?

import matplotlib.pyplot as plt
import numpy as np

# Generate data
x = np.linspace(0, 10, 100)
y = np.exp(-x/3) * np.sin(x)

plt.figure(figsize=(10, 6))
plt.plot(x, y, 'purple', linewidth=2)

# Add multiple text annotations
texts = [
    (1, 0.6, 'Peak 1', 'orange'),
    (4.2, -0.3, 'Valley', 'red'),
    (7.3, 0.15, 'Peak 2', 'blue'),
    (8.5, 0.1, 'Decay', 'green')
]

for x_pos, y_pos, text, color in texts:
    plt.text(x_pos, y_pos, text, fontsize=11, color=color,
             bbox=dict(facecolor='white', alpha=0.8, edgecolor=color))

plt.title('Damped Oscillation with Annotations')
plt.xlabel('Time')
plt.ylabel('Amplitude')
plt.grid(True, alpha=0.3)
plt.show()

Conclusion

Use plt.text() to add annotations at specific coordinates. Style text with font properties, colors, and background boxes. Use LaTeX syntax for mathematical expressions within dollar signs.