Code Modularity

The geo-path-reducer project is designed with a modular architecture that separates geometric calculations from the core path-simplification logic. This modularity allows for the encapsulation of specific mathematical formulas, such as the Haversine formula for great-circle distances and Heron's formula for perpendicular distance, while providing a clean API for the Douglas-Peucker algorithm. Sources: README.md, src/index.js

The project is structured as a modern ES module, utilizing export default for its primary functional units. This approach ensures that each component can be tested and maintained independently, contributing to the overall stability of the spatial data processing pipeline. Sources: package.json:11, src/distance.js:1, src/perpendicular-distance.js:3

Project Structure and Export Strategy

The repository follows a flat directory structure for its source code, located within the src/ directory. The main entry point is defined as src/index.js, which exposes the primary path reduction functionality. Sources: package.json:5

The following diagram illustrates the dependency flow between these modules:

The diagram shows how external consumers interact with the top-level reducer, which in turn relies on specialized geometric modules. Sources: src/index.js:1, src/perpendicular-distance.js:1

Geometric Calculation Layer

The modularity of the project is most evident in its calculation layer. Instead of embedding complex trigonometry within the main algorithm, the library delegates these tasks to specialized files.

Great-Circle Distance

The distance.js module calculates the distance between two points on Earth's surface using the Earth's radius (6371 km) and the Haversine formula. It accepts latitude and longitude coordinates and returns the distance in kilometers. Sources: src/distance.js:1-16

Perpendicular Distance

The perpendicular-distance.js module acts as an intermediary. It uses the distance function to calculate the lengths of the sides of a triangle formed by the target point and the line segment endpoints. It then applies the semi-perimeter calculation and Heron's formula to find the area and, subsequently, the perpendicular height. Sources: src/perpendicular-distance.js:3-11

The flowchart depicts the logical steps within the perpendicular distance module to derive the height from a point to a line. Sources: src/perpendicular-distance.js:5-11

Algorithm Implementation

The core logic resides in src/index.js. The geoPathReducer function serves as the public API. It identifies the point furthest from the line formed by the path's start and end points. If this maximum distance exceeds the provided epsilon threshold, the path is split and processed recursively. Sources: src/index.js:3-23

The sequence diagram demonstrates the recursive nature of the Douglas-Peucker implementation and its reliance on the perpendicular distance module. Sources: src/index.js:7-22

Configuration and Constants

The module's behavior is governed by the epsilon parameter provided by the user, which determines the degree of simplification. Sources: README.md:33-34

Sources: README.md:32-34, src/index.js:3

Conclusion

The modular design of geo-path-reducer ensures that the mathematical complexities of geographic distance calculations are isolated from the recursive logic of the path simplification algorithm. By utilizing standard ES modules and clear functional boundaries, the library remains easy to integrate and extend for various spatial data tasks.