# Functions

Here is a list of all functions included in H2GIS.

Function | Description |
---|---|

`CSVRead` |
CSV → Table |

`CSVWrite` |
Table → CSV |

`DBFRead` |
DBF → Table |

`DBFWrite` |
Table → DBF |

`DoubleRange` |
Return an array of doubles |

`FILE_TABLE` |
Link a table to a file |

`GPXRead` |
GPX → Table |

`GeoJsonRead` |
GeoJSON → Table |

`GeoJsonWrite` |
Table → GeoJSON |

`IntegerRange` |
Return an array of integers |

`JsonWrite` |
Table → JSON |

`KMLWrite` |
KML, KMZ → Table |

`OSMRead` |
OSM → Table |

`SHPRead` |
SHP → Table |

`SHPWrite` |
Table → SHP |

`ST_3DArea` |
Return a polygon's 3D area |

`ST_3DLength` |
Return the 3D length or the 3D perimeter of a Geometry |

`ST_3DPerimeter` |
Return the 3D perimeter of a (multi)polygon |

`ST_Accessibility` |
Calculate, from each vertex, the (distance to the) closest destination |

`ST_Accum` |
Construct an array of Geometries |

`ST_AddPoint` |
Add a point to a Geometry |

`ST_AddZ` |
Add a value to the z-coordinate of a Geometry |

`ST_Area` |
Return a Geometry's area |

`ST_AsBinary` |
Geometry → Well Known Binary |

`ST_AsGeoJson` |
Geometry → GeoJSON |

`ST_AsKML` |
Geometry → KML |

`ST_AsText` |
Alias for `ST_AsWKT` |

`ST_AsWKT` |
Geometry → Well Known Text |

`ST_Azimuth` |
Return the azimuth of the segment from point A to point B |

`ST_Boundary` |
Return a Geometry's boundary |

`ST_BoundingCircle` |
Return the minimum bounding circle of a Geometry |

`ST_Buffer` |
Compute a buffer around a Geometry |

`ST_Centroid` |
Return the centroid of a Geometry |

`ST_ClosestCoordinate` |
Return the coordinate(s) of a Geometry closest to a `POINT` |

`ST_ClosestPoint` |
Return the point of Geometry A closest to Geometry B |

`ST_CollectionExtract` |
Filter a Geometry with its dimension |

`ST_CompactnessRatio` |
Return the square root of a `POLYGON` 's area divided by the area of the circle with circumference equal to its perimeter |

`ST_ConnectedComponents` |
Calculate the (strongly) connected components of a graph |

`ST_ConstrainedDelaunay` |
Compute a constrained Delaunay triangulation based on a geometry |

`ST_Contains` |
Return true if Geometry A contains Geometry B |

`ST_ConvexHull` |
Compute the smallest convex `POLYGON` that contains all the points in the Geometry |

`ST_CoordDim` |
Return the dimension of the coordinates of a Geometry |

`ST_Covers` |
Return true if no point in Geometry B is outside Geometry A |

`ST_Crosses` |
Return true if Geometry A crosses Geometry B |

`ST_DWithin` |
Return true if the Geometries are within the specified distance of one another |

`ST_Delaunay` |
Compute a Delaunay triangulation based on points |

`ST_Densify` |
Insert extra vertices along the line segments of a Geometry |

`ST_Difference` |
Compute the difference between two geometries |

`ST_Dimension` |
Return the dimension of a Geometry |

`ST_Disjoint` |
Return true Geometries A and B are disjoint |

`ST_Distance` |
Return the distance between two Geometries |

`ST_Drape` |
Drape a geometry to a set of triangles |

`ST_EndPoint` |
Return the last coordinate of a `LINESTRING` |

`ST_Envelope` |
Return a Geometry's envelope as a Geometry |

`ST_EnvelopesIntersect` |
Return true if the envelope of Geometry A intersects the envelope of Geometry B |

`ST_Equals` |
Return true if Geometry A equals Geometry B |

`ST_Expand` |
Expand a Geometry's envelope |

`ST_Explode` |
Explode `GEOMETRYCOLLECTION` s into multiple Geometries |

`ST_Extent` |
Return the minimum bounding box of a `GEOMETRYCOLLECTION` |

`ST_ExteriorRing` |
Return the exterior ring of a `POLYGON` |

`ST_Extrude` |
Extrude a geometry |

`ST_FlipCoordinates` |
Flip the `X` and `Y` coordinates of a Geometry |

`ST_Force2D` |
3D Geometry → 2D Geometry |

`ST_Force3D` |
2D Geometry → 3D Geometry |

`ST_FurthestCoordinate` |
Compute the furthest coordinate(s) contained in a Geometry starting from a `POINT` |

`ST_GeomFromText` |
Well Known Text → Geometry |

`ST_GeomFromWKB` |
Well Known Binary → Geometry |

`ST_GeometryN` |
Return the nth Geometry of a `GEOMETRYCOLLECTION` |

`ST_GeometryShadow` |
Compute the shadow footprint for a single geometry |

`ST_GeometryType` |
Return the type of a Geometry |

`ST_GeometryTypeCode` |
Return the OGC SFS type code of a Geometry |

`ST_GoogleMapLink` |
Geometry → Google map link |

`ST_Graph` |
Produce nodes and edges tables from an input table containing `(MULTI)LINESTRINGS` |

`ST_GraphAnalysis` |
Calculate closeness/betweenness centrality of vertices and edges |

`ST_Holes` |
Return a Geometry's holes |

`ST_ISOVist` |
Compute the visibility from a point |

`ST_InteriorRingN` |
Return the nth interior ring of a `POLYGON` |

`ST_Interpolate3DLine` |
Return a Geometry with a interpolation of z values. |

`ST_Intersection` |
Compute the intersection of two Geometries |

`ST_Intersects` |
Return true if Geometry A intersects Geometry B |

`ST_Is3D` |
Return 1 if a Geometry has at least one z-coordinate; 0 otherwise |

`ST_IsClosed` |
Return true if a Geometry is a closed `LINESTRING` or `MULTILINESTRING` |

`ST_IsEmpty` |
Return true if a Geometry is empty |

`ST_IsRectangle` |
Return true if the Geometry is a rectangle |

`ST_IsRing` |
Return true if a `LINESTRING` is ring |

`ST_IsSimple` |
Return true if a Geometry is simple |

`ST_IsValid` |
Return true if the Geometry is valid |

`ST_IsValidDetail` |
Return a valid detail as an array of objects |

`ST_IsValidReason` |
Return text stating if a geometry is valid or not and if not valid, a reason why |

`ST_Length` |
Return the length of a Geometry |

`ST_LineFromText` |
Well Known Text → `LINESTRING` |

`ST_LineFromWKB` |
Well Known Binary → `LINESTRING` |

`ST_LineIntersector` |
Split an input `LINESTRING` with another geometry |

`ST_LineMerge` |
Merges a collection of linear components to form maximal-length `LINESTRING` |

`ST_LocateAlong` |
Return a `MULTIPOINT` containing points along the line segments of a Geometry at a given segment length fraction and offset distance |

`ST_LongestLine` |
Returns the 2-dimensional longest `LINESTRING` between the points of two geometries |

`ST_MLineFromText` |
Well Known Text → `MULTILINESTRING` |

`ST_MPointFromText` |
Well Known Text → `MULTIPOINT` |

`ST_MPolyFromText` |
Well Known Text → `MULTIPOLYGON` |

`ST_MakeEllipse` |
Construct an ellipse |

`ST_MakeEnvelope` |
Create a rectangular Polygon |

`ST_MakeGrid` |
Calculate a regular grid of `POLYGON` s based on a Geometry or a table of Geometries |

`ST_MakeGridPoints` |
Calculate a regular grid of `POINT` s based on a Geometry or a table of Geometries |

`ST_MakeLine` |
`(MULTI)POINT` → `LINESTRING` |

`ST_MakePoint` |
Construct a `POINT` from two or three coordinates |

`ST_MakePolygon` |
`LINESTRING` → `POLYGON` |

`ST_MaxDistance` |
Compute the maximum distance between two geometries |

`ST_MinimumDiameter` |
Return the minimum diameter of a Geometry |

`ST_MinimumRectangle` |
Return the minimum rectangle enclosing a Geometry |

`ST_MultiplyZ` |
Return a Geometry's z-values by a factor |

`ST_Node` |
Add nodes on a geometry for each intersection |

`ST_Normalize` |
Return a Geometry with a normal form |

`ST_NumGeometries` |
Return the number of Geometries in a `GEOMETRYCOLLECTION` |

`ST_NumInteriorRing` |
Alias for `ST_NumInteriorRings` |

`ST_NumInteriorRings` |
Return the number of interior rings of a Geometry |

`ST_NumPoints` |
Return the number of points in a Geometry |

`ST_OSMDownloader` |
OSM → File |

`ST_OSMMapLink` |
Geometry → OSM map link |

`ST_OctogonalEnvelope` |
Return the octogonal envelope of a Geometry |

`ST_OrderingEquals` |
Returns `TRUE` if Geometry A equals Geometry B and their coordinates and component Geometries are listed in the same order |

`ST_Overlaps` |
Return true if Geometry A overlaps Geometry B |

`ST_Perimeter` |
Return the perimeter of a (multi)polygon |

`ST_Point` |
Construct a `POINT` from two or three coordinates |

`ST_PointFromText` |
Well Known Text → `POINT` |

`ST_PointFromWKB` |
Well Known Binary → `POINT` |

`ST_PointN` |
Return the nth point of a `LINESTRING` |

`ST_PointOnSurface` |
Return an interior or boundary point of a Geometry |

`ST_PolyFromText` |
Well Known Text → `POLYGON` |

`ST_PolyFromWKB` |
Well Known Binary → `POLYGON` |

`ST_Polygonize` |
Create a `MULTIPOLYGON` from edges of Geometries |

`ST_PrecisionReducer` |
Reduce a Geometry's precision |

`ST_ProjectPoint` |
Project a `POINT` on a `(MULTI)LINESTRING` |

`ST_Relate` |
Return the DE-9IM intersection matrix of the two Geometries or true if they are related by the given intersection matrix |

`ST_RemoveHoles` |
Remove a Geometry's holes |

`ST_RemovePoints` |
Return a Geometry with vertices less |

`ST_RemoveRepeatedPoints` |
Remove repeated points from a Geometry |

`ST_Reverse` |
Reverse the vertex order of a Geometry |

`ST_Reverse3DLine` |
Potentially reverse a Geometry according to the z-values of its first and last coordinates |

`ST_RingBuffer` |
Return a `MULTIPOLYGON` of buffers centered at a Geometry and of increasing buffer Size |

`ST_RingSideBuffer` |
Compute a ring buffer on one side |

`ST_Rotate` |
Rotate a Geometry counter-clockwise by an angle (in radians) about a point |

`ST_SRID` |
Return a SRID value |

`ST_SVF` |
Compute the Sky View Factor |

`ST_Scale` |
Scale a Geometry by multiplying the ordinates by the indicated scale factors |

`ST_SetSRID` |
Return a copy of a Geometry with a new SRID |

`ST_ShortestLine` |
Returns the 2-dimensional shortest `LINESTRING` between two geometries |

`ST_ShortestPath` |
Calculate shortest path(s) between vertices in a graph |

`ST_ShortestPathLength` |
Calculate length(s) of shortest path(s) and distance matrices |

`ST_ShortestPathTree` |
Calculate shortest path tree from a vertex |

`ST_SideBuffer` |
Compute a single buffer on one side |

`ST_Simplify` |
Simplify a Geometry |

`ST_SimplifyPreserveTopology` |
Simplify a Geometry, preserving its topology |

`ST_Snap` |
Snap two Geometries together |

`ST_Split` |
Split Geometry A by Geometry B |

`ST_StartPoint` |
Return the first coordinate of a `LINESTRING` |

`ST_SunPosition` |
Compute the sun position |

`ST_SymDifference` |
Compute the symmetric difference between two Geometries |

`ST_Tessellate` |
Tessellate a set of Polygon with adaptive triangles |

`ST_ToMultiLine` |
Geometry's coordinates → `MULTILINESTRING` |

`ST_ToMultiPoint` |
Geometry's coordinates → `MULTIPOINT` |

`ST_ToMultiSegments` |
`GEOMETRY(COLLECTION)` → `MULTILINESTRING` |

`ST_Touches` |
Return true if Geometry A touches Geometry B |

`ST_Transform` |
Transform a Geometry from one CRS to another |

`ST_Translate` |
Translate a Geometry |

`ST_TriangleAspect` |
Return the aspect of a triangle |

`ST_TriangleContouring` |
Split triangles into smaller triangles according to classes |

`ST_TriangleDirection` |
Compute the direction of steepest ascent of a triangle |

`ST_TriangleSlope` |
Compute the slope of a triangle as a percentage |

`ST_Union` |
Compute the union of two or more Geometries |

`ST_UpdateZ` |
Update the z-values of a Geometry |

`ST_Voronoi` |
Create a Voronoi diagram. |

`ST_Within` |
Return true if Geometry A is within Geometry B |

`ST_X` |
Return the x-value of the first coordinate of a Geometry |

`ST_XMax` |
Return the maximum x-value of a Geometry |

`ST_XMin` |
Return the minimum x-value of a Geometry |

`ST_Y` |
Return the y-value of the first coordinate of a Geometry |

`ST_YMax` |
Return the maximum y-value of a Geometry |

`ST_YMin` |
Return the minimum y-value of a Geometry |

`ST_Z` |
Return the z-value of the first coordinate of a Geometry |

`ST_ZMax` |
Return the maximum z-value of a Geometry |

`ST_ZMin` |
Return the minimum z-value of a Geometry |

`ST_ZUpdateLineExtremities` |
Update the start and end z-values of a Geometry |

Documented functions: 182/182.