In this blog post, we will explore an issue faced while trying to rotate the legend horizontally in GeoPandas. We will delve into the solution and provide a step-by-step guide to resolve this problem.
The Problem:
When attempting to rotate the legend horizontally using the orientation
parameter in GeoPandas, you may encounter an unexpected behavior where the legend remains vertical.
This issue arises when the data type of the column used to create the colorbar is an object dtype. Matplotlib, which is used by GeoPandas for plotting, treats object dtype columns as discrete values, resulting in a discrete colorbar. In such cases, the orientation
parameter only works for colorbars and has no effect on the legend orientation.
The Solution:
To resolve this issue and enable horizontal legend rotation, you need to convert the object dtype column to a numeric data type. This can be achieved using the to_numeric()
method or by explicitly casting the column to a numeric type, such as int
or float
.
Once the column is converted to a numeric data type, you can proceed with creating the plot and specify the orientation
parameter to rotate the legend horizontally.
Step-by-Step Guide:
import geopandas as gpd
import matplotlib.pyplot as plt
# Read the data
data = gpd.read_file('path/to/data.shp')
# Convert the object dtype column to numeric
data['COUNTYFP'] = data['COUNTYFP'].to_numeric()
# Create the plot
fig, ax = plt.subplots()
data.plot(column='COUNTYFP', legend=True, ax=ax)
# Rotate the legend horizontally
ax.legend(orientation="horizontal")
# Display the plot
plt.show()
By following these steps, you can successfully rotate the legend horizontally in GeoPandas, allowing for a more visually appealing and informative plot.