File Structure Analysis
Relevant source files
The following files were used as context for generating this wiki page:
The geo-path-reducer library is a JavaScript module designed to simplify curves represented by a series of geographic points using the Douglas-Peucker algorithm. This simplification is essential for reducing the complexity of spatial data, such as map coordinates, while maintaining the overall shape of the path within a specified tolerance (epsilon).
The project follows a modular architecture where the core logic is divided into specialized utility functions for distance calculation and geometric analysis. The main entry point aggregates these utilities to perform recursive path reduction.
Sources: README.md:3-7, src/index.js:3-5
Module Organization and Dependencies
The project structure separates the mathematical logic from the main algorithm implementation. The following diagram illustrates the dependency flow between the internal modules.
The diagram above shows how the main entry point relies on geometric calculations which in turn rely on basic distance math.
Sources: package.json:5, src/index.js:1, src/perpendicular-distance.js:1
Core Components
Package Configuration
The package.json file identifies the module as an ES module ("type": "module") and specifies src/index.js as the primary entry point.
| Property | Value | Description |
|---|---|---|
name | geo-path-reducer | The npm package name. |
main | src/index.js | The entry point for the module. |
type | module | Indicates the use of ECMAScript modules. |
license | MIT | The legal license for the software. |
Sources: package.json:2-12
Entry Point: geoPathReducer
Located in src/index.js, this is the default export of the library. It implements the Douglas-Peucker algorithm by identifying the point with the maximum perpendicular distance from the line segment formed by the start and end points of the current path.
- Recursive Logic: If the maximum distance (
dmax) exceeds the providedepsilon, the path is split at that point, and the function calls itself (referenced asdouglasPeuckerinternally) on the left and right segments. - Base Case: If no point exceeds the
epsilondistance, only the start and end points are returned.
Sources: src/index.js:3-23
Mathematical Utilities
1. Perpendicular Distance (src/perpendicular-distance.js)
Calculates the shortest distance from a point to a line defined by two other points (start and end). It uses Heron's formula to find the area of the triangle formed by the three points and then derives the height (the perpendicular distance).
Sources: src/perpendicular-distance.js:3-11
2. Great-Circle Distance (src/distance.js)
Calculates the distance between two points on the Earth's surface using the Haversine formula.
const R = 6371; // Earth's radius in kilometers
// ... Haversine calculation ...
const d = R * c;
Sources: src/distance.js:3-15
Data Flow Analysis
The following sequence diagram demonstrates how the library processes an array of points.
The diagram shows the recursive nature of the algorithm and the chain of utility calls required for distance measurement.
Sources: src/index.js:6-23, src/perpendicular-distance.js:5-10
API Definition
The library exposes a single primary function through the main entry point.
| Parameter | Type | Description |
|---|---|---|
points | Array<Object> | An array of objects with lat and lng properties. |
epsilon | Number | The maximum distance (tolerance) for simplification. |
Sources: README.md:30-36, src/index.js:3
Summary of File Roles
package.json: Defines project metadata and module type.README.md: Provides usage examples and API documentation.src/index.js: Orchestrates the Douglas-Peucker recursive logic.src/perpendicular-distance.js: Logic for point-to-line distance using triangle area.src/distance.js: Low-level Haversine formula for geographic distance on Earth.
Sources: package.json, README.md, src/index.js, src/perpendicular-distance.js, src/distance.js