How to make xticks evenly spaced despite their values? (Matplotlib)

When plotting data with irregular x-values, Matplotlib automatically spaces ticks according to their actual values. To create evenly spaced ticks regardless of the underlying values, we can use set_ticks() and set_ticklabels() methods.

The Problem

By default, Matplotlib positions x-ticks based on their actual values. If your data has irregular spacing (like [1, 1.5, 3, 5, 6]), the ticks will be unevenly distributed on the plot.

Solution: Using set_ticks() and set_ticklabels()

We can override the default behavior by setting custom tick positions and labels ?

import numpy as np
from matplotlib import pyplot as plt

plt.rcParams["figure.figsize"] = [7.50, 3.50]
plt.rcParams["figure.autolayout"] = True

x = np.array([1, 1.5, 3, 5, 6])
y = np.power(2, x)

fig, (ax1, ax2) = plt.subplots(2, 1)

# Default behavior - ticks based on actual x values
ax1.plot(x, y)
ax1.xaxis.set_ticks(x)
ax1.set_title("Default: Unevenly spaced ticks")

# Even spacing - use sequential positions with original labels
ax2.plot(x, y)
ax2.xaxis.set_ticks(range(len(x)))
ax2.xaxis.set_ticklabels(x)
ax2.set_title("Even spacing: Sequential positions")

plt.show()

How It Works

The key is to separate tick positions from tick labels:

• set_ticks(range(len(x))) − Creates evenly spaced positions: [0, 1, 2, 3, 4]
• set_ticklabels(x) − Uses original values as labels: [1, 1.5, 3, 5, 6]

Alternative Approach: Using plt.xticks()

For single plots, you can use the shorthand plt.xticks() function ?

import numpy as np
from matplotlib import pyplot as plt

x = np.array([1, 1.5, 3, 5, 6])
y = np.power(2, x)

plt.figure(figsize=(8, 4))
plt.plot(x, y, marker='o')
plt.xticks(range(len(x)), x)
plt.title("Even spacing using plt.xticks()")
plt.grid(True, alpha=0.3)
plt.show()

Comparison

Conclusion

Use set_ticks(range(len(x))) with set_ticklabels(x) to create evenly spaced ticks regardless of actual x-values. This approach is particularly useful for categorical data or when you want consistent visual spacing.