spatial

package
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 Go to latest Published: Apr 4, 2022 License: Apache-2.0 Imports: 13 Imported by: 0

README

lib/spatial

lib/spatial is a small Golang library for handling geospatial data.

Its focus is on serializing/deserializing into standardized data formats: Currently it supports GeoJSON, WKB and TinyWKB (TWKB).

Documentation

Index

Constants

This section is empty.

Variables

View Source 
var (
	ErrorEmptyGeomType = errors.New("empty geometry type")
)

Functions

func LineSegmentToCarthesian 

func LineSegmentToCarthesian(p1, p2 Point) (a, b, c float64)

LineSegmentToCarthesian converts a line segment into a carthesian representation. Possible improvement: normalization of values

Types

type BBox 

type BBox struct {
	SW, NE Point
}

func (*BBox) ExtendWith 

func (b1 *BBox) ExtendWith(b2 BBox)

func (BBox) FullyIn 

func (b BBox) FullyIn(b2 BBox) bool

func (BBox) Overlaps 

func (b BBox) Overlaps(b2 BBox) bool

In determines if the bboxes overlap.

func (BBox) Segments 

func (b BBox) Segments() []Segment

type ChunkedDecoder 

type ChunkedDecoder interface {
	ChunkedDecode(io.Reader) (Chunks, error)
}

type ChunkedEncoder 

type ChunkedEncoder interface {
	EncodeChunk(io.Writer, *FeatureCollection) error
	Close(io.Writer) error
}

type Chunks 

type Chunks interface {
	Next() bool
	Scan(fc *FeatureCollection) error
}

type Clippable 

type Clippable interface {
	// TODO: consider returning primitive geom, instead of Geom
	ClipToBBox(BBox) []Geom
}

type Codec 

type Codec interface {
	Extensions() []string
}

A Codec needs to be able to tell which file extensions (e.g. "geojson") are commonly used to persist files. Moreover a Codec SHOULD either implement a Decoder or Encoder.

type ConvertFunc 

type ConvertFunc func(Point) Point

type Decoder 

type Decoder interface {
	Decode(io.Reader, *FeatureCollection) error
}

type Encoder 

type Encoder interface {
	Encode(io.Writer, *FeatureCollection) error
}

type Feature 

type Feature struct {
	Props    map[string]interface{} `json:"properties"`
	Geometry Geom
}

Feature is a data structure which holds geometry and tags/properties of a geographical feature.

func MergeFeatures 

func MergeFeatures(fts []Feature) []Feature

MergeFeatures aggregates features that have the same properties, if possible.

func NewFeature 

func NewFeature() Feature

func (Feature) MarshalJSON 

func (f Feature) MarshalJSON() ([]byte, error)

func (*Feature) MarshalWKB 

func (f *Feature) MarshalWKB() ([]byte, error)

func (*Feature) Properties 

func (f *Feature) Properties() map[string]interface{}

type FeatureCollection 

type FeatureCollection struct {
	Features []Feature `json:"features"`
	SRID     string    `json:"-"`

} // TODO: consider adding properties field

func NewFeatureCollection 

func NewFeatureCollection() *FeatureCollection

func (*FeatureCollection) Filter 

func (fc *FeatureCollection) Filter(bbox BBox) []Feature

func (FeatureCollection) MarshalJSON 

func (fc FeatureCollection) MarshalJSON() ([]byte, error)

Deprecated. Please use geojson.Codec.

func (*FeatureCollection) Reset 

func (fc *FeatureCollection) Reset()

Reset removes all features.

type Filterable 

type Filterable interface {
	Filter(BBox) []Feature
}

type Geom 

type Geom struct {
	// contains filtered or unexported fields
}

func GeomFromWKB 

func GeomFromWKB(r io.Reader) (Geom, error)

func MustNewGeom 

func MustNewGeom(g interface{}) Geom

func NewGeom 

func NewGeom(g interface{}) (Geom, error)

func (*Geom) BBox 

func (g *Geom) BBox() BBox

func (*Geom) ClipToBBox 

func (g *Geom) ClipToBBox(bbox BBox) []Geom

Clips a geometry and returns a cropped copy. Returns a slice, because clip might result in multiple sub-Geoms.

func (*Geom) Copy 

func (g *Geom) Copy() Geom

func (*Geom) LineString 

func (g *Geom) LineString() (Line, error)

func (Geom) MarshalJSON 

func (g Geom) MarshalJSON() ([]byte, error)

func (Geom) MarshalWKB 

func (g Geom) MarshalWKB() ([]byte, error)

TODO: maybe MarshalWKB could take an io.Writer instead of returning a buffer?

func (*Geom) MustLineString 

func (g *Geom) MustLineString() Line

func (*Geom) MustPoint 

func (g *Geom) MustPoint() *Point

func (*Geom) MustPolygon 

func (g *Geom) MustPolygon() Polygon

func (*Geom) Overlaps 

func (g *Geom) Overlaps(bbox BBox) bool

func (*Geom) Point 

func (g *Geom) Point() (*Point, error)

Point retruns the geometry as a point (check type with Typ()) first.

func (*Geom) Polygon 

func (g *Geom) Polygon() (Polygon, error)

func (Geom) Project 

func (g Geom) Project(fn ConvertFunc)

func (Geom) Simplify 

func (g Geom) Simplify(e float64) Geom

func (Geom) String 

func (g Geom) String() string

func (*Geom) Typ 

func (g *Geom) Typ() GeomType

Typ returns the geometries type.

func (*Geom) UnmarshalJSON 

func (g *Geom) UnmarshalJSON(buf []byte) error

func (*Geom) UnmarshalJSONCoords 

func (g *Geom) UnmarshalJSONCoords(typ string, inner json.RawMessage) error

func (*Geom) UnmarshalWKB 

func (g *Geom) UnmarshalWKB(r io.Reader) error

func (*Geom) ValidTopology 

func (g *Geom) ValidTopology() bool

type GeomType 

type GeomType uint32
const (
	GeomTypeEmpty      GeomType = 0
	GeomTypePoint      GeomType = 1
	GeomTypeLineString GeomType = 2
	GeomTypePolygon    GeomType = 3
	GeomTypeInvalid
)

func (GeomType) String 

func (g GeomType) String() string

type Line 

type Line []Point

func MergeLines 

func MergeLines(l1, l2 Line) Line

MergeLines is deprecated.

func NewLinesFromSegments 

func NewLinesFromSegments(segs []Segment) []Line

NewLinesFromSegments creates a line from continous segments.

func (Line) Area 

func (l Line) Area() float64

func (Line) BBox 

func (l Line) BBox() BBox

func (Line) Center 

func (l Line) Center() Point

func (Line) ClipToBBox 

func (l Line) ClipToBBox(bbox BBox) []Geom

func (Line) Clockwise 

func (l Line) Clockwise() bool

func (Line) Closed 

func (l Line) Closed() bool

func (Line) Copy 

func (l Line) Copy() Projectable

func (Line) Intersections 

func (l Line) Intersections(segments []Segment) []Point

func (Line) IsExtendedBy 

func (l1 Line) IsExtendedBy(l2 Line) bool

func (Line) Project 

func (l Line) Project(proj ConvertFunc)

func (Line) Reverse 

func (l Line) Reverse()

func (Line) Segments 

func (l Line) Segments() []Segment

Segments splits a Line into Segments (line with two points).

func (Line) SegmentsWithClosing 

func (l Line) SegmentsWithClosing() []Segment

func (Line) Simplify 

func (l Line) Simplify(e float64) Line

Simplify returns a simplified copy of the Line using the Ramer-Douglas-Peucker algorithm.

func (Line) String 

func (l Line) String() string

type Point 

type Point struct{ X, Y float64 }

func (Point) ClipToBBox 

func (p Point) ClipToBBox(b BBox) []Geom

func (Point) Copy 

func (p Point) Copy() Projectable

func (*Point) HaversineDistance 

func (p *Point) HaversineDistance(p2 *Point) float64

DistanceTo returns the distance in meters between the points.

func (Point) InBBox 

func (p Point) InBBox(b BBox) bool

func (Point) InPolygon 

func (p Point) InPolygon(poly Polygon) bool

func (Point) MarshalJSON 

func (p Point) MarshalJSON() ([]byte, error)

func (*Point) Project 

func (p *Point) Project(proj ConvertFunc)

func (Point) RoundedCoords 

func (p Point) RoundedCoords() Point

func (*Point) SetX 

func (p *Point) SetX(x float64)

func (*Point) SetY 

func (p *Point) SetY(y float64)

func (Point) String 

func (p Point) String() string

func (*Point) UnmarshalJSON 

func (p *Point) UnmarshalJSON(buf []byte) error

type Polygon 

type Polygon []Line

Polygon is a data type for storing simple polygons.

func (Polygon) ClipToBBox 

func (p Polygon) ClipToBBox(bbox BBox) []Geom

func (Polygon) Copy 

func (p Polygon) Copy() Projectable

func (Polygon) FixWinding 

func (p Polygon) FixWinding()

func (Polygon) MustJSON 

func (p Polygon) MustJSON() []byte

func (Polygon) Project 

func (p Polygon) Project(proj ConvertFunc)

func (Polygon) Rewind 

func (p Polygon) Rewind()

func (Polygon) String 

func (p Polygon) String() string

func (Polygon) ValidTopology 

func (p Polygon) ValidTopology() bool

type Projectable 

type Projectable interface {
	Project(ConvertFunc)
	Copy() Projectable
}

type PropertyRetriever 

type PropertyRetriever interface {
	Properties() map[string]interface{}
}

type RTreeCollection 

type RTreeCollection struct {
	// contains filtered or unexported fields
}

RTreeCollection is a FeatureCollection which is backed by a rtree.

func NewRTreeCollection 

func NewRTreeCollection(features ...Feature) *RTreeCollection

func (*RTreeCollection) Add 

func (rt *RTreeCollection) Add(feature Feature)

func (*RTreeCollection) Filter 

func (rt *RTreeCollection) Filter(bbox BBox) []Feature

type Segment 

type Segment [2]Point

func BBoxBorders 

func BBoxBorders(sw, ne Point) []Segment

BBoxBorders returns the lines which describe the rectangle of the BBox. Segments are returned in counter-clockwise order.

func (Segment) Bearing 

func (s Segment) Bearing() float64

Bearing returns the heading direction between the first and the second point in degrees.

func (*Segment) ClipToBBox 

func (s *Segment) ClipToBBox(sw, ne Point) []Segment

ClipToBBox returns 0 or 1 Segment which is inside bbox.

func (Segment) DistanceToPt 

func (s Segment) DistanceToPt(p Point) float64

DistanceToPt determines the Segment's perpendicular distance to the point.

func (*Segment) FullyInBBox 

func (s *Segment) FullyInBBox(sw, ne Point) bool

func (*Segment) HasPoint 

func (s *Segment) HasPoint(pt Point) bool

func (*Segment) Intersection 

func (s *Segment) Intersection(s2 Segment) (Point, bool)

LineIntersect returns a point where the two lines intersect and whether the point is on both segments.

func (*Segment) JSON 

func (s *Segment) JSON() []byte

func (*Segment) Length 

func (s *Segment) Length() float64

func (*Segment) SplitAt 

func (s *Segment) SplitAt(p Point) (Segment, Segment)

type Validatable 

type Validatable interface {
	ValidTopology() bool
}

type WKBable 

type WKBable interface {
	MarshalWKB() ([]byte, error)
}

type WKBableWithProps 

type WKBableWithProps interface {
	WKBable
	PropertyRetriever
}

Source Files

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