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Spatial K

Turf

Turf.js is a spatial analysis library for JavaScript applications. The turf module is a Kotlin port with support for Kotlin Multiplatform and Java projects.

This module uses the classes from the geojson module as GeoJSON inputs to turf functions.

Documentation for ported functions can be found in the API docs, while details on each function are available on the Turf.js site.

Installation

Section titled “Installation”
commonMain {
    dependencies {
        implementation("org.maplibre.spatialk:turf:0.8.0")
    }
}

Example

Section titled “Example”

Turf functions are available as top-level functions in Kotlin and as static methods in Java.

val point = Position(-75.0, 45.0)
val (longitude, latitude) = point.offset(100.kilometers, Bearing.North)

Ported Functions

Section titled “Ported Functions”

Measurement

Section titled “Measurement”

Coordinate Mutation

Section titled “Coordinate Mutation”
  • cleanCoords
  • flip
  • rewind
  • round
  • truncate

Transformation

Section titled “Transformation”
  • bboxClip
  • bezierSpline
  • buffer
  • circle
  • clone
  • concave
  • convex
  • difference
  • dissolve
  • intersect
  • lineOffset
  • simplify
  • tessellate
  • transformRotate
  • transformTranslate
  • transformScale
  • union
  • voronoi

Feature Conversion

Section titled “Feature Conversion”

Geometry-preserving conversions keep bbox and foreignMembers. combine and explode rebuild new geometries from coordinates and drop both.

Miscellaneous

Section titled “Miscellaneous”

Helper

Section titled “Helper”

Use the GeoJson DSL instead.

Random

Section titled “Random”
  • randomPosition
  • randomPoint
  • randomLineString
  • randomPolygon

Data

Section titled “Data”
  • sample

Interpolation

Section titled “Interpolation”
  • interpolate
  • isobands
  • isolines
  • planepoint
  • tin

Joins

Section titled “Joins”

Grids

Section titled “Grids”

Classification

Section titled “Classification”

Aggregation

Section titled “Aggregation”
  • collect
  • clustersDbscan
  • clustersKmeans

Meta

Section titled “Meta”

Many GeoJson objects implement Collection, enabling standard Kotlin collection operations to replace Turf meta functions.

Assertions

Section titled “Assertions”
  • collectionOf
  • containsNumber
  • geojsonType
  • featureOf

Booleans

Section titled “Booleans”
  • booleanClockwise
  • booleanContains
  • booleanCrosses
  • booleanDisjoint
  • booleanEqual
  • booleanOverlap
  • booleanParallel
  • booleanPointInPolygon
  • booleanPointOnLine
  • booleanWithin

Unit Conversion

Section titled “Unit Conversion”

For converting between units of length, area, and angle, see the Units module.

  • toMercator
  • toWgs84