RasterCollection.extract: Extract

In flahn/raster-collection: Extending functions of the raster package to handle spatio-temporal image collections

Description

The extract function wraps the similar called function of the raster package, with the twist that it is not loading that much data into memory. We will use a polygons bounding box and extract those relatively small subsets directly from multiple files using GDAL (rgdal). We have also the possibility to state a custom row handling which might be used to inject extracted values directly into a database or write it to a file. Otherwise it will create a large tibble table that resides in memory.

Arguments

geoms	SpatialPolygon or SpatialPolygonsDataFrame that shall be used for extraction
fun	the function that will be passed to raster::extract function
raster.fun	function of the raster package that is applied when building an image format in R, when loading the small bounding boxes for polygons (raster as default)
col.id	the name of the polygon id column when creating the row data.frame ("id" as default)
attribute.names	character vector that labels the columns for calculated attributes for the row data.frame
row.handler	a function that defines custom behavior how to deal with the row (extracted values) if omitted or NULL a tibble will be created
cpuLoad	if a row.handler is specified this parameter is used to calculate the amount of cores used to reach the targeted cpu load (values between 0 and 1)

Value

a tibble if row.handler is omitted otherwise it is void

flahn/raster-collection documentation built on May 21, 2019, 12:04 p.m.