How to Calculate Distance between Two Points using GEOPY

Use Geopy’s distance module in order to calculate distance between two points. The Geopy package offers several tools that provide distance between geographic points on the Earth’s surface through different algorithms, like the geodesic(great-circle distance) and Vincenty. Here’s an explanation in detail:

Installation

First, ensure you have the Geopy library installed. You can install it using pip:

pip install geopy

Basics of Geopy

Geopy provides:

• geopy.distance.geodesic: This is used for the shortest distance on Earth’s surface, and which is generally accurate in almost all applications.
• geopy.distance.great_circle: This is a faster but less accurate calculation that assumes a perfect sphere for the Earth.

Steps to Calculate Distance

1. Define the coordinates: latitude and longitude for each point.
   • Example: Point 1 = (latitude1, longitude1) and Point 2 = (latitude2, longitude2).
2. Use the Geopy distance module:
   • Import the appropriate method (e.g., geodesic or great_circle).
   • Pass the coordinates as tuples to the method.

Example Code

Here’s a complete example:

from geopy.distance import geodesic, great_circle

# Define coordinates (latitude, longitude)
point1 = (37.7749, -122.4194)  # San Francisco, CA
point2 = (34.0522, -118.2437)  # Los Angeles, CA

# Calculate distance using geodesic
geodesic_distance = geodesic(point1, point2).kilometers
print(f"Geodesic Distance: {geodesic_distance:.2f} km")

# Calculate distance using great_circle
great_circle_distance = great_circle(point1, point2).kilometers
print(f"Great Circle Distance: {great_circle_distance:.2f} km")

Output Example

For the above code (distance between San Francisco and Los Angeles):

Geodesic Distance: 559.14 km
Great Circle Distance: 559.17 km

Explanation of Methods

1. geodesic:

• Uses the WGS-84 ellipsoid model of the Earth, which makes it more accurate.
• For applications where precision matters the most.

2. great_circle:

• Assumes Earth is a perfect sphere.
• Faster but less accurate (the error increases with longer distances).

Real-World Applications

1. Travel Planning: Calculate distances between cities for logistics.
2. Mapping Software: Measure distances for navigation apps.
3. Geospatial Analysis: Analyze geographic data for research or business.

Key Notes

• Make sure coordinates are in decimal degrees (e.g., 37.7749, not 37°46'30\"N).
• Choose a method with the optimal trade-off between accuracy and performance.
• For very small distances, both geodesic and great_circle give nearly the same answer.