Module Categories

Purpose and Scope

This document explains the functional categorization of Turf.js modules into seven distinct groups based on their operational purpose. The 100+ packages in the Turf.js monorepo are organized by the type of geospatial operation they perform, ranging from basic measurements to complex geometric algorithms. This categorization helps users discover appropriate modules for their use cases and understand the library's operational capabilities.

For information about the foundational utilities that underpin all categories, see Foundation Modules. For details on how modules depend on each other across tiers, see Dependency Hierarchy.

Category Overview

The Turf.js modules are organized into seven functional categories, each serving a distinct operational domain. All categories depend on the foundation layer (@turf/helpers, @turf/meta, @turf/invariant) described in Foundation Modules.

100%

Measurement Modules

Measurement modules calculate quantitative properties of geographic features, including distances, bearings, areas, and lengths. These modules typically implement geodesic calculations using the WGS84 ellipsoid.

Core Measurement Operations

100%

Module Listing

Module	Description	Key Dependencies
@turf/distance	Geodesic distance between two points	@turf/helpers, @turf/invariant
@turf/bearing	Geographic bearing between points	@turf/helpers, @turf/invariant
@turf/destination	Calculate destination point from origin, distance, and bearing	@turf/helpers, @turf/invariant
@turf/along	Point at specified distance along a line	@turf/bearing, @turf/destination, @turf/distance
@turf/area	Geodesic area of polygons in square meters	@turf/helpers, @turf/meta
@turf/length	Total length of LineStrings	@turf/helpers, @turf/meta
@turf/bbox	Calculate bounding box	@turf/helpers, @turf/meta
@turf/midpoint	Midpoint between two points	@turf/bearing, @turf/destination, @turf/distance

Boolean Predicate Modules

Boolean predicate modules perform spatial relationship tests between geometries, returning true or false. These modules implement standard topological predicates from the DE-9IM spatial model.

Boolean Operations Mapping

100%

Predicate Categories

Category	Modules	Typical Use Case
Containment	boolean-contains, boolean-within, boolean-point-in-polygon	Determine if features are inside/outside boundaries
Intersection	boolean-intersects, boolean-crosses, boolean-overlap	Detect geometric overlap or crossing
Separation	boolean-disjoint, boolean-touches	Test spatial separation or adjacency
Equivalence	boolean-equal	Compare geometries for equality
Validation	boolean-valid, boolean-clockwise, boolean-concave	Validate geometric properties
Line Relationships	boolean-parallel, boolean-point-on-line	Test linear feature relationships

Transformation Modules

Transformation modules modify the geometry or coordinates of features without changing their fundamental structure. These operations include coordinate manipulation, shape modification, and precision control.

Transformation Operations

100%

Module Characteristics

Module	Input Type	Output Type	External Dependencies
@turf/buffer	Point/Line/Polygon	Polygon	@turf/jsts, d3-geo
@turf/simplify	Line/Polygon	Line/Polygon	@turf/clean-coords
@turf/truncate	Any Feature	Same Feature	None
@turf/flip	Any Feature	Same Feature	@turf/clone, @turf/meta
@turf/clean-coords	Line/Polygon	Line/Polygon	None
@turf/transform-rotate	Any Feature	Same Feature	@turf/clone, @turf/meta
@turf/transform-scale	Any Feature	Same Feature	@turf/clone, @turf/meta
@turf/transform-translate	Any Feature	Same Feature	@turf/clone, @turf/meta

Geometric Operations

Geometric operations perform complex algorithmic transformations on features, including boolean operations, hull calculations, and line processing. These modules often depend on external computational geometry libraries.

Boolean Set Operations

100%

Hull and Envelope Operations

100%

Line Processing Modules

Module	Operation	Dependencies
@turf/line-split	Split line by point or line	@turf/meta, @turf/nearest-point-on-line
@turf/line-segment	Break line into segments	@turf/meta
@turf/line-chunk	Divide line into equal chunks	@turf/meta, @turf/length
@turf/line-intersect	Find intersection points	sweepline-intersections
@turf/line-overlap	Find overlapping portions	@turf/meta
@turf/line-offset	Parallel offset lines	@turf/meta
@turf/line-slice	Extract segment between points	@turf/nearest-point-on-line
@turf/line-slice-along	Extract segment by distance	@turf/along, @turf/length

Complex Polygon Operations

Module	Description	Key External Library
@turf/union	Combine multiple polygons	polyclip-ts
@turf/intersect	Find shared polygon area	polyclip-ts
@turf/difference	Subtract one polygon from another	polyclip-ts
@turf/concave	Generate concave hull	topojson-server, topojson-client
@turf/convex	Generate convex hull	concaveman
@turf/unkink-polygon	Fix self-intersections	rbush
@turf/mask	Create inverted polygon	polyclip-ts
@turf/dissolve	Merge polygons by property	polyclip-ts
@turf/polygonize	Create polygons from lines	@turf/jsts
@turf/tesselate	Triangulate polygon	earcut
@turf/voronoi	Voronoi diagram	d3-delaunay

Grid Generation Modules

Grid generation modules create regular tessellations of a bounding box area. These modules produce FeatureCollections of polygons or points arranged in geometric patterns.

Grid Types and Implementation

100%

Grid Module Specifications

Module	Cell Shape	Parameters	Special Dependencies
@turf/hex-grid	Regular hexagon	cellSide, units, triangles option	@turf/distance, @turf/intersect
@turf/square-grid	Square	cellSide, units, mask option	@turf/rectangle-grid
@turf/triangle-grid	Equilateral triangle	cellSide, units, mask option	@turf/distance, @turf/intersect
@turf/point-grid	N/A (points)	cellSide, units, mask option	@turf/boolean-within, @turf/distance
@turf/rectangle-grid	Custom rectangle	cellWidth, cellHeight, units	None (base implementation)

Cell Size and Units

All grid modules accept a cell size parameter and a units option. Supported units include:

• 'miles' - Statute miles
• 'kilometers' - Metric kilometers
• 'degrees' - Decimal degrees
• 'radians' - Angular radians
• 'meters', 'centimeters', 'feet', etc.

The unit conversion is handled by @turf/helpers functions convertLength() and convertArea().

Clustering and Analysis Modules

Clustering and analysis modules perform statistical operations, data interpolation, and pattern analysis on geospatial features. These modules often use spatial indexing for performance.

Clustering Algorithms

100%

Center Calculations

100%

Interpolation and Contour Generation

Module	Purpose	Algorithm/Library	Output
@turf/interpolate	Estimate values for unsampled locations	Inverse distance weighting	Point grid with interpolated values
@turf/isolines	Generate contour lines	marchingsquares library	LineString contours at specified levels
@turf/isobands	Generate filled contour polygons	marchingsquares library	Polygon bands between value ranges
@turf/tin	Triangulated irregular network	Delaunay triangulation	Polygon triangles for surface modeling
@turf/planepoint	Interpolate from TIN surface	Planar interpolation	Estimated z-value at point

Statistical Analysis Modules

Module	Analysis Type	Dependencies
@turf/standard-deviational-ellipse	Directional distribution	@turf/center-mean, @turf/ellipse
@turf/nearest-neighbor-analysis	Spatial clustering test	@turf/distance
@turf/moran-index	Spatial autocorrelation	@turf/distance-weight
@turf/quadrat-analysis	Point pattern analysis	@turf/square-grid

Data Manipulation Modules

Data manipulation modules restructure GeoJSON data without performing geometric calculations. These operations transform feature collections, aggregate properties, or modify feature types.

Structure Transformation

100%

Property Aggregation

100%

Data Manipulation Operations

Module	Operation	Input	Output	Use Case
@turf/flatten	Flatten Multi* geometries	MultiPoint/MultiLineString/MultiPolygon	Multiple single geometries	Simplify structure for processing
@turf/explode	Extract all coordinates	Any feature	Point for each coordinate	Get all vertices
@turf/combine	Merge by geometry type	Mixed FeatureCollection	Multi* features by type	Group related features
@turf/collect	Aggregate point values into polygons	Points + Polygons	Polygons with aggregated properties	Summarize data by zone
@turf/tag	Transfer polygon properties to points	Points + Polygons	Points with polygon properties	Spatial join operation
@turf/clone	Deep copy features	Any feature	Independent copy	Preserve original data
@turf/sample	Random subset	FeatureCollection	Subset FeatureCollection	Statistical sampling
@turf/random	Generate random features	None	Random Point/Line/Polygon	Testing and simulation

Line and Polygon Conversions

Module	Conversion	Dependencies
@turf/line-to-polygon	LineString → Polygon	Validates closure
@turf/polygon-to-line	Polygon → LineString	Extracts rings
@turf/bezier-spline	LineString → Smooth curve	Cubic Bézier interpolation
@turf/polygon-smooth	Polygon → Smoothed polygon	Chaikin's algorithm

Category Usage Patterns

Typical Module Combination Patterns

The following patterns represent common workflows that combine modules from multiple categories:

Pattern 1: Spatial Join Analysis

1. @turf/hex-grid (Grid Generation) → Create analysis grid
2. @turf/collect (Data Manipulation) → Aggregate point data into hexagons
3. @turf/center-mean (Clustering) → Find center of each hex
4. @turf/buffer (Transformation) → Create zones around centers

Pattern 2: Route Analysis

1. @turf/length (Measurement) → Calculate total route length
2. @turf/line-chunk (Geometric Operations) → Split into equal segments
3. @turf/along (Measurement) → Find points at regular intervals
4. @turf/buffer (Transformation) → Create corridor around route

Pattern 3: Contour Mapping

1. @turf/point-grid (Grid Generation) → Create sample grid
2. @turf/interpolate (Clustering) → Estimate values at grid points
3. @turf/isolines (Clustering) → Generate contour lines
4. @turf/simplify (Transformation) → Reduce contour complexity