rxtractogon: Extract environmental data in a polygon using 'ERDDAP™' and...
In rerddapXtracto: Extracts Environmental Data from 'ERDDAP™' Web Services

rxtractogon

R Documentation

Extract environmental data in a polygon using 'ERDDAP™' and 'rerddap'.

Description

rxtractogon uses the R program 'rerddap' to extract environmental data from an 'ERDDAP™' server in a polygon through time.

Usage

rxtractogon(
  dataInfo,
  parameter,
  xcoord = NULL,
  ycoord = NULL,
  zcoord = NULL,
  tcoord = NULL,
  xName = "longitude",
  yName = "latitude",
  zName = "altitude",
  tName = "time",
  verbose = FALSE,
  cache_remove = TRUE
)

Arguments

`dataInfo`	- the return from an 'rerddap:info' call to an 'ERDDAP™' server
`parameter`	- character string containing the name of the parameter to extract
`xcoord`	- array giving longitudes (in decimal degrees East, either 0-360 or -180 to 180) of polygon
`ycoord`	- array giving latitudes (in decimal degrees N; -90 to 90)of polygon
`zcoord`	- a real number with the z-coordinate(usually altitude or depth)
`tcoord`	- 2-array of minimum and maximum times as 'YYYY-MM-DD'
`xName`	- character string with name of the xcoord in the 'ERDDAP™' dataset (default "longitude")
`yName`	- character string with name of the ycoord in the 'ERDDAP™' dataset (default "latitude")
`zName`	- character string with name of the zcoord in the 'ERDDAP™' dataset (default "altitude")
`tName`	- character string with name of the tcoord in the 'ERDDAP™' dataset (default "time")
`verbose`	- logical variable (default FALSE) if the the URL request should be verbose
`cache_remove`	- logical variable (default TRUE) whether to delete 'rerddap' cache

Value

If successful a structure with data and dimensions

extract$data - the masked data array dimensioned (lon,lat,time)
extract$varname - the name of the parameter extracted
extract$datasetname - ERDDAP dataset name
extract$longitude - the longitudes on some scale as request
extract$latitude - the latitudes always going south to north
extract$time - the times of the extracts

else an error string

Details

rxtractogon extracts the data from the smallest bounding box that contains the polygon, and then uses the function "point.in.polygon" from the "sp" package to mask out the areas outside of the polygon. rxtractogon only works with datasets defined on a latitude and longitude grid.

Examples

## toy example to show use
## and keep execution time low
# dataInfo <- rerddap::info('erdHadISST')
parameter <- 'sst'
tcoord <- c("2016-06-15")
xcoord <- mbnms$Longitude[1:3]
ycoord <- mbnms$Latitude[1:3]
# sanctSST <- rxtractogon (dataInfo, parameter=parameter, xcoord = xcoord,
#                          ycoord = ycoord,  tcoord= tcoord)
#
## MBMS bathymetry example
xcoord <- mbnms$Longitude
ycoord <- mbnms$Latitude
dataInfo <- rerddap::info('etopo180')
parameter = 'altitude'
xName <- 'longitude'
yName <- 'latitude'
# bathy <- rxtractogon (dataInfo, parameter = parameter, xcoord = xcoord, ycoord = ycoord)

rerddapXtracto documentation built on Sept. 11, 2024, 5:19 p.m.