How to add a variable to Python plt.title?

To add a variable to Python plt.title(), you can use string formatting methods like f-strings, format(), or the % operator. This allows you to dynamically include variable values in your plot titles.

Basic Example with Variable in Title

Here's how to include a variable in your matplotlib title ?

import numpy as np
import matplotlib.pyplot as plt

# Set figure properties
plt.rcParams["figure.figsize"] = [7.00, 3.50]
plt.rcParams["figure.autolayout"] = True

# Create data points
x = np.linspace(-1, 1, 10)
num = 2
y = num ** x

# Plot with variable in title
plt.plot(x, y, c='red')
plt.title(f"y = {num}^x")
plt.show()

Different String Formatting Methods

Using f-strings (Recommended)

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(0, 10, 100)
slope = 2.5
intercept = 1.2
y = slope * x + intercept

plt.plot(x, y)
plt.title(f"Linear Function: y = {slope}x + {intercept}")
plt.show()

Using format() Method

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(0, 2*np.pi, 100)
amplitude = 3
frequency = 2
y = amplitude * np.sin(frequency * x)

plt.plot(x, y)
plt.title("Sine Wave: y = {}sin({}x)".format(amplitude, frequency))
plt.show()

Using % Operator

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-5, 5, 100)
coefficient = 0.5
y = coefficient * x**2

plt.plot(x, y)
plt.title("Quadratic Function: y = %.1fx²" % coefficient)
plt.show()

Multiple Variables in Title

You can include multiple variables in your title ?

import matplotlib.pyplot as plt
import numpy as np

# Parameters
n_points = 50
mean = 5
std_dev = 2

# Generate data
data = np.random.normal(mean, std_dev, n_points)

plt.hist(data, bins=10, alpha=0.7)
plt.title(f"Normal Distribution (n={n_points}, ?={mean}, ?={std_dev})")
plt.xlabel("Value")
plt.ylabel("Frequency")
plt.show()

Comparison of Methods

Conclusion

Use f-strings for the most readable code when adding variables to plot titles. The format() method works well for complex formatting, while the % operator is useful for simple numeric displays.