How to change the transparency/opaqueness of a Matplotlib Table?

In Matplotlib, you can control the transparency (alpha value) of table cells to create visually appealing tables. The set_alpha() method allows you to adjust opacity, where 0.0 is completely transparent and 1.0 is completely opaque.

Steps to Change Table Transparency

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

• Create a figure and a set of subplots.

• Create a random dataset with 10×3 dimension.

• Create a tuple of columns.

• Get rid of the axis markers using axis('off').

• Create a table with data and columns.

• Iterate each cell of the table and change its transparency using set_alpha() method.

• Display the figure using show() method.

Example

import numpy as np
from matplotlib import pyplot as plt

plt.rcParams["figure.figsize"] = [7.00, 3.50]
plt.rcParams["figure.autolayout"] = True

fig, axs = plt.subplots(1, 1)
data = np.random.random((10, 3))
columns = ("Column I", "Column II", "Column III")

axs.axis('off')

the_table = axs.table(cellText=data, colLabels=columns, loc='center')

for k, cell in the_table._cells.items():
    cell.set_edgecolor('black')
    if k[0] == 0 or k[1] < 0:
        cell.set_text_props(weight='bold', color='w')
        cell.set_facecolor('red')
        cell.set_alpha(0.5)
    else:
        cell.set_facecolor(['green', 'yellow'][k[0] % 2])
        cell.set_alpha(0.5)

plt.show()

Understanding Alpha Values

The set_alpha() method accepts values between 0.0 and 1.0 ?

import numpy as np
from matplotlib import pyplot as plt

fig, axs = plt.subplots(1, 1)
data = [['Transparent', 'Semi-transparent', 'Opaque']]
columns = ('Alpha=0.2', 'Alpha=0.5', 'Alpha=1.0')

axs.axis('off')
the_table = axs.table(cellText=data, colLabels=columns, loc='center')

# Set different alpha values for demonstration
alpha_values = [0.2, 0.5, 1.0]
for i, (k, cell) in enumerate(the_table._cells.items()):
    if k[0] == 0:  # Header row
        cell.set_facecolor('blue')
        cell.set_text_props(weight='bold', color='white')
        cell.set_alpha(alpha_values[k[1]])
    else:  # Data row
        cell.set_facecolor('lightblue')
        cell.set_alpha(alpha_values[k[1]])

plt.title('Table Transparency Examples')
plt.show()

Key Points

• Alpha = 0.0: Completely transparent (invisible)

• Alpha = 0.5: Semi-transparent (50% opacity)

• Alpha = 1.0: Completely opaque (default)

• Use the_table._cells.items() to iterate through all table cells

• Cell coordinates are stored as tuples (row, column) where row 0 is the header

Conclusion

Use the set_alpha() method to control table cell transparency in Matplotlib. Values range from 0.0 (transparent) to 1.0 (opaque), allowing you to create layered visual effects and improve table readability.