get_extent: Retrieve the joint extent of all specified spatial objects

Description Usage Arguments Author(s) Examples

View source: R/helper_funs.R

Description

Retrieve the joint extent of all specified spatial objects by running through a parameter-argument list while merging the extents of all spatial objects. This is mostly needed for the GRASS_REGION_PARAMETER. Still there are geoalgorithms which require an extent object.

Usage

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get_extent(params, type_name)

Arguments

params

A parameter-argument list as returned by get_args_man() or pass_args(), which contains all spatial objects from which the joint extent should be retrieved.

type_name

A character string containing the QGIS parameter type for each parameter (boolean, multipleinput, extent, number, etc.) of params. The Python method RQGIS.get_args_man() returns a Python dictionary with one of its elements corresponding to the type_name (see also the example section).

Author(s)

Jannes Muenchow

Examples

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## Not run: 
library("RQGIS")
library("raster")
library("reticulate")
r = raster(ncol = 100, nrow = 100)
r1 = crop(r, extent(-10, 11, -10, 11))
r2 = crop(r, extent(0, 20, 0, 20))
r3 = crop(r, extent(9, 30, 9, 30))
r1[] = 1:ncell(r1)
r2[] = 1:ncell(r2)
r3[] = 1:ncell(r3)
alg = "grass7:r.patch"
out = py_run_string(sprintf("out = RQGIS.get_args_man('%s')", alg))$out
params = get_args_man(alg)
params$input = list(r1, r2, r3)
get_extent(params = params, type_name = out$type_name)
# or if we save the input rasters in files stored on disk
params[] = save_spatial_objects(params = params,
                                 type_name = out$type_name)
get_extent(params = params, type_name = out$type_name)

## End(Not run)

jannes-m/RQGIS3 documentation built on Dec. 2, 2018, 12:17 p.m.