How to put text at the corner of an equal aspect figure in Python/Matplotlib?

To put text at the corner of an equal aspect figure in Matplotlib, you can use the annotate() method with xycoords='axes fraction' parameter. This allows you to position text using relative coordinates where (0,0) is the bottom-left corner and (1,1) is the top-right corner.

Steps to Add Corner Text

• Set the figure size and adjust the padding between and around the subplots.

• Create a figure and a set of subplots using subplots() method.

• Create x data points using NumPy.

• Plot data on different axes using plot() method.

• Use annotate() method with xycoords='axes fraction' to position text at corners.

• Display the figure using show() method.

Example

Here's how to add text at different corners of subplot axes ?

import matplotlib.pyplot as plt
import numpy as np

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

fig, axes = plt.subplots(2)
x = np.linspace(-2, 2, 10)

axes[0].plot(x)
axes[1].plot(x, 2*x)

for ax in axes:
    ax.annotate('Top Right', xy=(1, 1), xycoords='axes fraction', 
                fontsize=10, horizontalalignment='right', 
                verticalalignment='top')
    
    ax.annotate('Bottom Left', xy=(0, 0), xycoords='axes fraction',
                fontsize=10, horizontalalignment='left',
                verticalalignment='bottom')

plt.show()

Corner Position Coordinates

When using xycoords='axes fraction', the coordinates work as follows ?

Advanced Example with Multiple Corners

You can add text to all four corners of a single plot ?

import matplotlib.pyplot as plt
import numpy as np

fig, ax = plt.subplots(figsize=(6, 6))
x = np.linspace(0, 2*np.pi, 100)
y = np.sin(x)

ax.plot(x, y, 'b-', linewidth=2)
ax.set_aspect('equal')

# Add text to all four corners
corners = [
    ((0, 0), 'Bottom Left', 'left', 'bottom'),
    ((1, 0), 'Bottom Right', 'right', 'bottom'),
    ((0, 1), 'Top Left', 'left', 'top'),
    ((1, 1), 'Top Right', 'right', 'top')
]

for (x_pos, y_pos), text, h_align, v_align in corners:
    ax.annotate(text, xy=(x_pos, y_pos), xycoords='axes fraction',
                fontsize=12, horizontalalignment=h_align,
                verticalalignment=v_align, bbox=dict(boxstyle='round,pad=0.3', 
                facecolor='yellow', alpha=0.7))

plt.title('Text at All Four Corners')
plt.show()

Key Parameters

• xy − Coordinates where to place the text

• xycoords='axes fraction' − Use relative coordinates (0-1 range)

• horizontalalignment − Text alignment ('left', 'center', 'right')

• verticalalignment − Vertical alignment ('top', 'center', 'bottom')

• fontsize − Size of the text

• bbox − Optional background box styling

Conclusion

Use annotate() with xycoords='axes fraction' to position text at corners using relative coordinates. Combine with proper alignment parameters for precise corner placement in equal aspect figures.