考虑这个可重复的例子：

import numpy as np
import matplotlib.pyplot as plt
labels = ['0','1','2','3','4','5','6','7','8','9','10','11','12','13','14','15','16','17','18','19','20','21']
fig, axes = plt.subplots(nrows=3, ncols=3,figsize=(6, 3.5),dpi=300)
plt.subplots_adjust(wspace=0.025, hspace=0.2)
for ax in [a for b in axes for a in b]:
    ax.imshow(np.random.randint(2, size=(22,42)))
    ax.set_xticks([0,6,12,18,24,30,36,41])
    ax.tick_params(axis='x', which='major', labelsize=3)
    ax.set_yticks([])
    ax.set_aspect('equal')
for ax in [item for sublist in axes for item in sublist][0::3]:
    ax.set_yticks(range(len(labels)))
    ax.set_yticklabels(labels,fontsize=3)
fig.savefig("example.png",bbox_inches='tight')

我的问题是，即使我改变了刻度的字体大小，每个刻度的线条仍然保持不变。这看起来很难看，浪费了很多空间，特别是在X轴上。有什么想法如何使这些线条更小，从而使xlabel更接近轴？
PS tight_layout()没有帮助。