Matplotlib图表X轴刻度标签未全部显示且位置异常的问题排查与解决咨询

I get it—dealing with wonky tick labels in dual-axis plots can be frustrating. Let’s break down what’s going wrong and fix it step by step:

Key Issues & Fixes #

• Missing labels: You’re setting tick labels without first defining exactly where the ticks should go. Matplotlib defaults to sparse ticks if you don’t specify positions, so only a subset of your defect names get displayed.
• Misaligned positions: Without explicit tick positions, labels end up offset from their corresponding bars. We need to lock ticks to every row in your DataFrame.
• Label clipping/ mess: Rotating labels helps, but adding right alignment will keep them neat and prevent them from getting cut off by the figure edge.

Updated Working Code #

Here’s your revised code with all fixes applied:

import matplotlib.pyplot as plt
from matplotlib.ticker import PercentFormatter

fig, ax1 = plt.subplots()
fig.set_figheight(7)
fig.set_figwidth(12)

# Bar plot on primary axis
ax1.bar(df.index, df['occurence of defects'], color="C0")
ax1.set_ylabel("Qty", color="C0")
ax1.tick_params(axis="y", colors="C0")
ax1.set_xlabel("Defect")

# Critical fix: Define tick positions first, then labels with alignment
ax1.set_xticks(df.index)  # Ensures one tick per defect in your DataFrame
ax1.set_xticklabels(df['Name of Defect'], rotation=45, ha='right')  # Right-align rotated labels for readability

# Line plot on secondary axis
ax2 = ax1.twinx()
ax2.plot(df.index, df["cum percentage"], color="C1", marker="D", ms=7)
ax2.yaxis.set_major_formatter(PercentFormatter())
ax2.tick_params(axis="y", colors="C1")

# Optional but helpful: Auto-adjust margins to avoid label clipping
plt.tight_layout()

plt.show()

What Changed? #

1. ax1.set_xticks(df.index): This forces Matplotlib to place a tick at every index position in your DataFrame, so every defect name gets a corresponding label.
2. ha='right' in set_xticklabels(): Rotated labels now align to the right edge of their tick, making them look clean and centered above each bar.
3. plt.tight_layout(): This automatically adjusts the plot’s margins to ensure all rotated labels fit without getting cut off.

After these changes, all your X-axis labels should be visible, perfectly aligned with their bars, and easy to read!

内容的提问来源于stack exchange，提问作者user18013381