How to plot multiple horizontal bars in one chart with matplotlib?

To plot multiple horizontal bars in one chart with matplotlib, you can use the barh() method with different y-positions for each data series. This creates grouped horizontal bar charts that allow easy comparison between multiple datasets.

Steps

• Import the required libraries: matplotlib, numpy, and pandas (if needed)

• Set the figure size and layout parameters

• Create arrays for bar positions and define bar width

• Use barh() to create horizontal bars with offset positions

• Configure y-axis ticks and labels

• Add a legend to distinguish between data series

• Display the plot using show()

Example

Here's how to create a horizontal bar chart with two data series ?

import matplotlib.pyplot as plt
import numpy as np

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

# Array for horizontal bar's position
ind = np.array([0, 1, 2])

# Bar's width
width = 0.4

fig, ax = plt.subplots()

# Horizontal bar plot
ax.barh(ind, np.array([4, 3, 5]), width, color='orange', label='Series N')
ax.barh(ind + width, np.array([2, 5, 2]), width, color='blue', label='Series M')

# Set Y-axis ticks and ticklabels
ax.set(yticks=ind + width/2, yticklabels=np.array(['Category A', 'Category B', 'Category C']),
       ylim=[-0.5, len(ind)])

# Legend at the upper right corner
ax.legend(loc='upper right')

# Add labels
ax.set_xlabel('Values')
ax.set_ylabel('Categories')
ax.set_title('Multiple Horizontal Bar Chart')

# Display the plot
plt.show()

Output

The code produces a horizontal bar chart with two data series displayed side by side ?

Advanced Example with More Data Series

You can add more data series by adjusting the y-positions ?

import matplotlib.pyplot as plt
import numpy as np

# Data
categories = ['Product A', 'Product B', 'Product C', 'Product D']
q1_sales = [20, 35, 30, 25]
q2_sales = [25, 30, 35, 30]
q3_sales = [30, 25, 20, 35]

# Position settings
y_pos = np.arange(len(categories))
bar_height = 0.25

# Create the plot
fig, ax = plt.subplots(figsize=(10, 6))

# Create horizontal bars
bars1 = ax.barh(y_pos - bar_height, q1_sales, bar_height, label='Q1', color='skyblue')
bars2 = ax.barh(y_pos, q2_sales, bar_height, label='Q2', color='orange')
bars3 = ax.barh(y_pos + bar_height, q3_sales, bar_height, label='Q3', color='lightgreen')

# Customize the chart
ax.set_xlabel('Sales (in thousands)')
ax.set_ylabel('Products')
ax.set_title('Quarterly Sales Comparison')
ax.set_yticks(y_pos)
ax.set_yticklabels(categories)
ax.legend()

# Add grid for better readability
ax.grid(axis='x', alpha=0.3)

plt.tight_layout()
plt.show()

Key Parameters

Conclusion

Use barh() with offset y-positions to create multiple horizontal bar series. Adjust the bar width and positioning to prevent overlap and ensure clear visualization of your data comparisons.