gps-0.4.0: For manipulating GPS coordinates and trails.




Author: Thomas DuBuisson Copyright: Thomas DuBuisson License: BSD3

A basic GPS library with calculations for distance and speed along with helper functions for filtering/smoothing trails. All distances are in meters and time is in seconds. Speed is thus meters/second

The current intent of this library is to 1) Provide a standard type class interface for coordinates 2) Include fleshed out support for relevant libraries, a task too often neglected in modern Hackage packages.

Integration includes KML support via the xml package, pretty printing, anb binary.


Types and Classes

class Coordinate a whereSource

A coordinate is a place on earths surface. While twoDMS and fromDMS are the only required functions, coordinate systems may provide more accurate calculations of heading, distance, and vectors without the intermediate translation.

class Coordinate coord => Location loc coord time | loc -> coord, loc -> time whereSource

A location is a coordinate at a specific time


getCoordinate :: loc -> coordSource

getTime :: loc -> timeSource

getUTC :: loc -> UTCTimeSource

speed :: loc -> loc -> SpeedSource


data DMSCoordinate Source

DMSCoordinate is the typical degree minute second for latitude/longitude used by most civilian GPS devices.



data DMS a Source

DMS is the degrees, minutes, seconds used for both latitude and longitude




Eq (DMS a) 
Ord (DMS a) 
Read (DMS a) 
Show (DMS a) 

data Latitude Source

Empty declaration for phantom type

data Longitude Source

Empty declaration for phantom type

type Distance = DoubleSource

Distances are expressed in meters

type Heading = DoubleSource

Angles are expressed in radians from North. 0 == North pi/2 == West pi == South (32)pi == East == - (pi 2)

type Speed = DoubleSource

Speed is hard coded as meters per second

type Trail a = [a]Source


north :: HeadingSource

North is 0 radians

south :: HeadingSource

South, being 180 degrees from North, is pi.

east :: HeadingSource

East is 270 degrees from North

west :: HeadingSource

West is 90 degrees (pi/2)

radiusOfEarth :: DoubleSource

radius of the earth in meters

Helper Functions

smoothTrails :: Location a b c => Speed -> Trail a -> [Trail a]Source

smoothTrails speed trail should separate points that would mandate a speed in excess of the given rate into separate Trails. No point are deleted; if there is only one correct trail expected then the largest resulting trail will likely be the one your looking for.

longestSmoothTrail :: Location a b c => Speed -> Trail a -> Trail aSource

Uses smoothTrails but returns only the longest resulting trail

restLocations :: Location a b c => Distance -> NominalDiffTime -> Trail a -> [Trail a]Source

Creates a list of trails all of which are within the given distance of each other spanning atleast the given amount of time.

For example restLocations 50 600 would return lists of all points that are within 50 meters of each other and span at least 10 minutes (600 seconds).

Note this gives points within fifty meters of the earliest point - wandering in a rest area with a 50 meter radius could result in several rest points ([a,b..]) or even none if the distance between individual points exceeds 50m.

closestDistance :: Coordinate a => Trail a -> Trail a -> Maybe DistanceSource

Returns the closest distance between two trails (or Nothing if a trail is empty) O( (n * m) * log (n * m) )

normalizeDMS :: DMSCoordinate -> DMSCoordinateSource

Typically useful for printing, normalizes degrees, minutes, seconds into just degrees and decimal minutes:

DMSCoord (DMS 45 36.938455 0) (DMS ...)

dmsToDegreePair :: DMSCoordinate -> (Double, Double)Source

Provides a lat/lon pair of doubles in degrees

dmsToRadianPair :: DMSCoordinate -> (Double, Double)Source

Provides a lat/lon pair of doubles in radians

addVector :: Vector -> DMSCoordinate -> DMSCoordinateSource

Given a vector and coordinate, computes a new DMS coordinate. Within some epsilon it should hold that if

dest = addVector (dist,heading) start


heading == dmsHeading start dest
dist    == distance start dest

divideArea :: Distance -> Distance -> DMSCoordinate -> DMSCoordinate -> [[DMSCoordinate]]Source

divideArea vDist hDist nw se divides an area into a grid of equally spaced coordinates within the box drawn by the northwest point (nw) and southeast point (se). Because this uses floating point there might be a different number of points in some rows (the last might be too far east based on a heading from the se point).