How to produce a barcode in Matplotlib?

To produce a barcode in Matplotlib, you can create a visual representation using binary data (0s and 1s) where 1s represent black bars and 0s represent white spaces. This technique uses imshow() to display the binary pattern as a barcode-like image.

Basic Barcode Creation

Here's how to create a simple barcode using a binary array ?

import matplotlib.pyplot as plt
import numpy as np

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

# Binary pattern for barcode (1 = black bar, 0 = white space)
code = np.array([
   1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1,
   0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0,
   1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 1,
   1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1
])

# Create figure with specified DPI
fig = plt.figure(dpi=100)

# Add axes that fill the entire figure
ax = fig.add_axes([0, 0, 1, 1])
ax.set_axis_off()

# Display the barcode using imshow
ax.imshow(code.reshape(1, -1), cmap='binary', aspect='auto',
          interpolation='nearest')

plt.show()

Creating a More Realistic Barcode

For a more barcode-like appearance, you can adjust the aspect ratio and add labels ?

import matplotlib.pyplot as plt
import numpy as np

# Create a shorter, more realistic barcode pattern
barcode_data = np.array([1, 0, 1, 1, 0, 0, 1, 0, 1, 1, 1, 0, 0, 1, 0, 1, 
                        0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 0])

fig, ax = plt.subplots(figsize=(8, 2))

# Create barcode image
ax.imshow(barcode_data.reshape(1, -1), cmap='binary', aspect='auto')

# Remove axes and add title
ax.set_xticks([])
ax.set_yticks([])
ax.set_title('Sample Barcode', fontsize=12, pad=10)

# Add barcode number below
plt.figtext(0.5, 0.1, '1234567890123', ha='center', fontsize=10, 
            fontfamily='monospace')

plt.tight_layout()
plt.show()

Key Parameters

Customizing Barcode Appearance

You can modify colors and styling for different barcode types ?

import matplotlib.pyplot as plt
import numpy as np

# Generate random barcode pattern
np.random.seed(42)
barcode_pattern = np.random.choice([0, 1], size=50, p=[0.4, 0.6])

fig, (ax1, ax2) = plt.subplots(2, 1, figsize=(10, 4))

# Standard black and white barcode
ax1.imshow(barcode_pattern.reshape(1, -1), cmap='binary', aspect='auto')
ax1.set_title('Standard Barcode')
ax1.set_xticks([])
ax1.set_yticks([])

# Colored barcode
ax2.imshow(barcode_pattern.reshape(1, -1), cmap='Blues', aspect='auto')
ax2.set_title('Colored Barcode')
ax2.set_xticks([])
ax2.set_yticks([])

plt.tight_layout()
plt.show()

Conclusion

Creating barcodes in Matplotlib involves using imshow() with binary arrays and the 'binary' colormap. The reshape(1, -1) method converts the data into a horizontal barcode format, while aspect='auto' ensures proper bar proportions.