Table of Contents

geo

CONTENTS
Functions
Types

geo defines geographic operations in two-dimensional space

Functions

Point

Point(x,y) Point

Point constructor, takes an x(longitude) and y(latitude) value and returns a Point object

parameters:

name	type	description
`x`	`float`	x-dimension value (longitude if using geodesic space)
`y`	`float`	y-dimension value (latitude if using geodesic space)

examples:

stonehenge

create a point at the Stonehenge prehistoric monument in the United Kingdom

load("geo.star", "geo")
# create a point at 51.1789° N, 1.8262° W, use negative y (latitude) value for
# west quadrant
stonehenge = geo.Point(51.1789, -1.8262)
print(stonehenge)
# Output: (51.178900,-1.826200)

Line

Line(points) Line

Line constructor. Takes either an array of coordinate pairs or an array of point objects and returns the line that connects them. Points do not need to be collinear, providing a single point returns a line with a length of 0

parameters:

name	type	description
`points`	`[[]float	Point]`

Polygon

Polygon(rings) Polygon

Polygon constructor. Takes a list of lists of coordinate pairs (or point objects) that define the outer boundary and any holes / inner boundaries that represent a polygon. In GIS tradition, lists of coordinates that wind clockwise are filled regions and anti-clockwise represent holes.

parameters:

name	type	description
`rings`	`[Line]`	list of closed lines that constitute the polygon

MultiPolygon

MultiPolygon(polygons) MultiPolygon

MultiPolygon constructor. MultiPolygon groups a list of polygons to behave like a single polygon

parameters:

name	type	description
`polygons`	`[Polygon]`

within

within(geom,polygon) bool

Returns True if geom is entirely contained by polygon

parameters:

name	type	description
`geom`	`[point,line,polygon]`	maybe-inner geometry
`polygon`	`[Polygon,MultiPolygon]`	maybe-outer polygon

parseGeoJSON

parseGeoJSON(data) (geoms, properties)

Parses string data in IETF-7946 (GeoJSON) format (https://tools.ietf.org/html/rfc7946) returning a list of geometries and equal-length list of properties for each geometry

parameters:

name	type	description
`data`	`string`	string of GeoJSON data

examples:

FeatureCollection

parse example

load("geo.star", "geo")
geo_json_string = """
{
"type": "FeatureCollection",
"features": [{
"type": "Feature",
"properties": {
"name": "Coors Field"
},
"geometry": {
"type": "Point",
"coordinates": [-104.99404, 39.75621]
}
}, {
"type": "Feature",
"properties": {
"name": "Busch Field"
},
"geometry": {
"type": "Point",
"coordinates": [-104.98404, 39.74621]
}
}]
}
"""
(geoms, props) = geo.parseGeoJSON(geo_json_string)
print(props)
# Output: [{"name": "Coors Field"}, {"name": "Busch Field"}]

distance(p2) float

Euclidean Distance to the other point

parameters:

name	type	description
`p2 point`	``	point to measure distance to

distanceGeodesic

distanceGeodesic(p2) float

Distance on the surface of a sphere with the same radius as Earth

parameters:

name	type	description
`p2`	`point`	point to measure distance to

Line

an ordered list of points that define a line

Methods

length

length() float

Euclidean Length

lengthGeodesic

lengthGeodesic() float

Line length on the surface of a sphere with the same radius as Earth

Polygon

an ordered list of closed lines (rings) that define a shape. lists of coordinates that wind clockwise are filled regions and anti-clockwise represent holes.### MultiPolygon

MultiPolygon groups a list of polygons to behave like a single polygon

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CONTENTS
Functions
Types