Title positioning

Matplotlib can display plot titles centered, flush with the left side of a set of axes, and flush with the right side of a set of axes.

import matplotlib.pyplot as plt

plt.plot(range(10))

plt.title('Center Title')
plt.title('Left Title', loc='left')
plt.title('Right Title', loc='right')

plt.show()

The vertical position is automatically chosen to avoid decorations (i.e. labels and ticks) on the topmost x-axis:

fig, axs = plt.subplots(1, 2, layout='constrained')

ax = axs[0]
ax.plot(range(10))
ax.xaxis.set_label_position('top')
ax.set_xlabel('X-label')
ax.set_title('Center Title')

ax = axs[1]
ax.plot(range(10))
ax.xaxis.set_label_position('top')
ax.xaxis.tick_top()
ax.set_xlabel('X-label')
ax.set_title('Center Title')
plt.show()

Automatic positioning can be turned off by manually specifying the y keyword argument for the title or setting rcParams["axes.titley"] (default: None) in the rcParams.

fig, axs = plt.subplots(1, 2, layout='constrained')

ax = axs[0]
ax.plot(range(10))
ax.xaxis.set_label_position('top')
ax.set_xlabel('X-label')
ax.set_title('Manual y', y=1.0, pad=-14)

plt.rcParams['axes.titley'] = 1.0    # y is in axes-relative coordinates.
plt.rcParams['axes.titlepad'] = -14  # pad is in points...
ax = axs[1]
ax.plot(range(10))
ax.set_xlabel('X-label')
ax.set_title('rcParam y')

plt.show()