intersect_points {ALA4R}R Documentation

Intersect environmental or contextual layers at a given a set of points (coordinates)

Description

Intersect environmental or contextual layers at a given a set of points (coordinates)

Usage

intersect_points(pnts, layers, SPdata.frame = FALSE, use_layer_names = TRUE,
  verbose = ala_config()$verbose)

Arguments

pnts

numeric: vector of latitude/longitude pairs, or a 2 column data.frame or matrix of lat,lons. NOTE: the number of locations must be less than 100000.

layers

string vector: ids of layers to be intersected. The list of possible layers is available from ala_fields("layers"). Names can be passed as full layer names (e.g. "Radiation - lowest period (Bio22)") rather than id ("el871"). Note: if more than one location has been provided in pnts, the number of layers must be less than 700.

SPdata.frame

logical: should the output should be returned as a SpatialPointsDataFrame of the sp package or simply as a data.frame?

use_layer_names

logical: if TRUE, layer names will be used as column names in the returned data frame (e.g. "radiationLowestPeriodBio22"). Otherwise, layer id value will be used for column names (e.g. "el871")

verbose

logical: show additional progress information? [default is set by ala_config]

Value

A SpatialPointsDataFrame containing the intersecting data information. Missing data or incorrectly identified layer id values will result in NA data

Author(s)

Atlas of Living Australia support@ala.org.au

References

http://api.ala.org.au/

http://spatial.ala.org.au/layers/

This function allows the user to sample environmental/contextual layers at arbitrary locations. It complements the occurrences function, which allows values of the same set of layers to be downloaded at species occurrence locations. NOTE: batch requests (multiple points) are currently processed in a *single queue* on the ALA servers. Processing times may be slow if there are many requests in the queue. Note also that the actual processing of batch requests is inherently slow: a large number of points may take quite some time. Be warned.

See Also

ala_config

Examples

#single point with multiple layers
layers = c('cl22','cl23','el773')
pnts = c(-23.1,149.1)
intersect_points(pnts,layers)
# equivalent direct web service call: http://spatial.ala.org.au/ws/intersect/cl22,cl23,el773/-23.1/149.1
## Not run: 
## multiple points as a grid sampling multiple layers
## not run here because it's pretty slow
layers = c('cl22','cl23','el773')
pnts = data.frame(expand.grid(lat=seq(-29,-19,2.0),lon=seq(130.0,140.0,2.0)))
intersect_points(pnts,layers)

## End(Not run)

[Package ALA4R version 1.01 Index]