| Safe Haskell | Safe |
|---|---|
| Language | Haskell2010 |
OSRef
Description
To represent an Ordnance Survey of Great Britain (OSGB) grid reference.
British National Grid Projection: Transverse Mercator Reference ellipsoid: Airy 1830 Units: metres Origin: 49°N, 2°W False co-ordinates of origin: 400000m east, -100000m north
A full reference includes a two-character code identifying a particular 100,000m grid square. The table below shows how the two-character 100,000m grid squares are identified. The bottom left corner is at the false origin of the grid. Squares without values fall outside the boundaries of the British National Grid.
km 0 100 200 300 400 500 600 700
1200 HL HM HN HO HP JL JM
1100 HQ HR HS HT HU JQ JR
1000 HV HW HX HY HZ JV JW
900 NA NB NC ND NE OA OB
800 NF NG NH NJ NK OF OG OH
700 NL NM NN NO NP OL OM ON
600 NQ NR NS NT NU OQ OR OS
500
NW NX NY NZ OV OW OX
400
SB SC SD SE TA TB TC
300
SG SH SJ SK TF TG TH
200
SM SN SO SP TL TM TN
100 SQ SR SS ST SU TQ TR TS
0 SV SW SX SY SZ TV TW
Within each 100,000m square, the grid is further subdivided into 1000m squares. These 1km squares are shown on Ordnance Survey 1:25000 and 1:50000 mapping as the main grid. To reference a 1km square, give the easting and then the northing, e.g. TR2266. In this example, TR represents the 100,000m square, 22 represents the easting (in km) and 66 represents the northing (in km). This is commonly called a four-figure grid reference.
When providing local references, the 2 characters representing the 100,000m square are often omitted.
- data OSRef = OSRef {}
- data Precision
- scaleFactor :: Double
- falseOriginLatitude :: Double
- falseOriginLongitude :: Double
- falseOriginEasting :: Double
- falseOriginNorthing :: Double
- mkOSRef :: Double -> Double -> Except String OSRef
- mkOSRef' :: String -> Except String OSRef
- toOSRef :: LatLng -> Except String OSRef
- getOsRefWithPrecisionOf :: Precision -> OSRef -> String
- evalOsRef :: Double -> Double -> Double -> String
- toLatLng :: OSRef -> Except String LatLng
- evalEasting :: Double -> Except String Double
- evalNorthing :: Double -> Except String Double
Documentation
Constructors
| OSRef | |
Constructors
| SixDigits | A six-figure representation this OSGB grid reference i.e XY123456 |
| EightDigits | A eight-figure representation this OSGB grid reference i.e XY12345678 |
scaleFactor :: Double Source #
Arguments
| :: Double | The easting in metres. Must be greater than or equal to 0.0 and less than 800000.0. |
| -> Double | The northing in metres. Must be greater than or equal to 0.0 and less than 1400000.0. |
| -> Except String OSRef | Throws an exception if either the easting or the northing are invalid. |
Create a new Ordnance Survey grid reference using a given easting and northing. The easting and northing must be in metres and must be relative to the origin of the British National Grid.
Arguments
| :: String | a String representing a six-figure Ordnance Survey grid reference in the form XY123456 |
| -> Except String OSRef | Throws an exception if ref is not of the form XY123456. |
Take a string formatted as a six-figure OS grid reference (e.g. TG514131) and create a new OSRef object that represents that grid reference. The first character must be H, N, S, O or T. The second character can be any uppercase character from A through Z excluding I.
toOSRef :: LatLng -> Except String OSRef Source #
Convert latitude and longitude into an OSGB (Ordnance Survey of Great Britain) grid reference.
Convert this OSGB grid reference to a latitude/longitude pair using the OSGB36 datum. Note that, the LatLng object may need to be converted to the WGS84 datum depending on the application.