How to Set a Single Main Title for All the Subplots in Matplotlib?

Prerequisites: Matplotlib

A title in matplotlib library describes the main subject of plotting the graphs. Setting a title for just one plot is easy using the title() method. By using this function only the individual title plots can be set but not a single title for all subplots. Hence, to set a single main title for all subplots, suptitle() method is used.

Syntax: suptitle(self, t, **kwargs)

Parameters: This method accept the following parameters that are discussed below:

• t : This parameter is the title text.
• x: This parameter is the x location of the text in figure coordinates.
• y: This parameter is the y location of the text in figure coordinates.
• horizontalalignment, ha : This parameter is the horizontal alignment of the text relative to (x, y).
• verticalalignment, va : This parameter is the vertical alignment of the text relative to (x, y).
• fontsize, size : This parameter is the font size of the text.
• fontweight, weight : This parameter is the font weight of the text.

Returns: This method returns the Text instance of the title.

Approach

• Import module
• Create data to be plotted
• Set figure title using suptitle()
• Plot the graph
• Display plot

Implementation using approach given is given below:

Example 1:

Python3

import matplotlib.pyplot as plt
import numpy as np

fig, (ax1, ax2) = plt.subplots(1, 2, figsize=(12, 5))

x1 = [1, 2, 3, 4, 5, 6]
y1 = [45, 34, 30, 45, 50, 38]
y2 = [36, 28, 30, 40, 38, 48]

labels = ["student 1", "student 2"]

fig.suptitle(' Student marks in different subjects ', fontsize=30)

# Creating the sub-plots.
l1 = ax1.plot(x1, y1, 'o-', color='g')
l2 = ax2.plot(x1, y2, 'o-')

fig.legend([l1, l2], labels=labels,
           loc="upper right")
plt.subplots_adjust(right=0.9)

plt.show()

Output:

Example 2: 

Python3

import matplotlib.pyplot as plt
import numpy as np

fig, ax = plt.subplots(2, 2)
fig.suptitle('** Main Title for all sub plots **', fontsize=20)
plt.style.use('seaborn')

labels = ['first line', 'second line',
          'third line', 'fourth line', 'fifth line']

ax[0, 0].plot([1, 2, 3, 4, 5], [9, 3, 5, 7, 9], '-.', color='g')
ax[0, 0].set_title('first subplot')
ax[0, 0].set_yticks(np.arange(1, 10))

ax[0, 1].plot([1, 2, 3, 4, 5, 6], [1, 4, 9, 7, 9, 8], '-*', color='m')
ax[0, 1].set_title('second subplot')
ax[0, 1].set_yticks(np.arange(1, 10))

ax[1, 0].plot([1, 2, 3, 4, 5], [8, 5, 2, 3, 3], '-v', color='r')
ax[1, 0].set_title('third subplot')
ax[1, 0].set_yticks(np.arange(1, 9))

ax[1, 1].plot([1, 2, 3, 4, 5, 6], [1, 3, 5, 7, 9, 6], 'o-', color='b')
ax[1, 1].plot([1, 2, 3, 4, 5, 6, 7, 7], [
              7, 8, 6, 5, 2, 2, 4, 6], 'o-', color='g')
ax[1, 1].set_title('fourth subplot')
ax[1, 1].set_yticks(np.arange(1, 10))

fig.tight_layout()
fig.legend(ax, labels=labels, loc="upper right", borderaxespad=0.1)
fig.subplots_adjust(top=0.85)

plt.show()

Output: