geopyspark.geotrellis.key_conversion module

A module to provide facilites for converting between layout keys and spatial objects. These facilities aim to bridge between the various layouts, SpatialKeys, and geometry.

class geopyspark.geotrellis.key_conversion.KeyTransform(layout, crs=None, extent=None, cellsize=None, dimensions=None)

Provides functions to move from keys to geometry and vice-versa.

Tile Layers have an underlying RDD which is keyed by either SpatialKey or SpaceTimeKey. Each key represents a region in space, depending on a choice of layout. In order to enable the conversion of keys to regions, and of geometry to keys, the KeyTransform class is provided. This class is constructed with a layout, which is either GlobalLayout, LocalLayout, or a LayoutDefinition. Global layouts use power-of-two pyramids over the world extent, while local layouts operate over a defined extent and cellsize.

NOTE: LocalLayouts will encompass the requested extent, but the final layout may include ``SpatialKey``s which only partially cover the requested extent. The upper-left corner of the resulting layout will match the requested extent, but the right and bottom edges may be beyond the boundaries of the requested extent.

NOTE: GlobalLayouts require pyproj to be installed.

:param layout(GlobalLayout or LocalLayout: or LayoutDefinition): a definition of the layout scheme defining the key structure. :param crs: Used only when layout is GlobalLayout. Target CRS of reprojection.

Either EPSG code, well-known name, or a PROJ.4 string

Parameters:

• extent (Extent) – Used only for ``LocalLayout``s. The area of interest.
• cellsize (tup of (float, float)) – Used only for LocalLayout``s.  The (width, height) in extent units of a pixel. Cannot be specified simultaneously with ``dimensions.
• dimensions (tup of (int, int)) – Used only for LocalLayout``s.  The number of (columns, rows) of pixels over the entire extent.  Cannot be specified simultaneously with ``cellsize.

extent_to_keys(extent)

Returns the keys in the layout intersecting/covered by a given extent.

Parameters:extent (Extent) – The extent to find the matching keys for. Returns:[SpatialKey]

geometry_to_keys(geom)

Returns the keys corresponding to grid cells that intersect/are covered by a given Shapely geometry.

Parameters:geom (Geometry) – The geometry to find the matching keys for. Returns:[SpatialKey]

key_to_extent(key, *args)

Returns the Extent corresponding to a given key.

Parameters:key (SpatialKey or SpaceTimeKey or int) – The key to find the extent for. If of type int, then this parameter is the column of the key, and the call must provide a single additional int value in the args parameter to serve as the row of the key. Returns:Extent