Extracts Environmental Data from 'ERDDAP™' Web Services.

rerddapXtracto (Version 1.2.0)

rerddapXtracto - R package for accessing environmental data using 'rerddap'

rxtracto()now works in coordinate space for projected data

tidy_grid()function to convert result of 'rxtracto_3D()' or 'rxtractogon()' to "tidy"" long-format

rxtracto()option to use the ERDDAP™ "Interpolate service", which can greatly speed up extracts for large tracks.

rxtracto() major rewrite of this function to reduce the number of requests made to the ERDDAP server, and to improve overall speed.

rerddapXtracto is an R package developed to subset and extract satellite and other oceanographic related data from a remote ERDDAP™ server. The program can extract data for a moving point in time along a user-supplied set of longitude, latitude, time and depth points; in a 3D bounding box; or within a polygon (through time).

There are also two plotting functions, plotTrack() and plotBox() that make use of the plotdap package. See the new rerdapXtracto vignette.

There are three main data extraction functions in the rerddapXtracto package:

• rxtracto <- function(dataInfo, parameter = NULL, xcoord = NULL, ycoord = NULL, zcoord = NULL, tcoord = NULL, xlen = 0., ylen = 0., zlen = 0., xName = 'longitude', yName = 'latitude', zName = 'altitude', tName = 'time', interp = NULL, verbose = FALSE, progress_bar = FALSE)

• rxtracto_3D <- function(dataInfo, parameter = NULL, xcoord = NULL, ycoord = NULL, zcoord = NULL, tcoord = NULL, xName = 'longitude', yName = 'latitude', zName = 'altitude', tName = 'time', verbose = FALSE)

• rxtractogon <- function(dataInfo, parameter, xcoord = NULL, ycoord = NULL, zcoord = NULL, tcoord = NULL, xName = 'longitude', yName = 'latitude', zName = 'altitude', tName = 'time', verbose = FALSE)

and two functions for producing maps:

• plotTrack <- function(resp, xcoord, ycoord, tcoord, plotColor = 'viridis', myFunc = NA, mapData = NULL, crs = NULL, animate = FALSE, cumulative = FALSE, name = NA, shape = 20, size = .5)

• plotBBox <- function(resp, plotColor = 'viridis', time = NA, myFunc = NA, mapData = NULL, crs = NULL, animate = FALSE, cumulative = FALSE, name = NA, maxpixels = 10000)

and function to convert result of 'rxtracto_3D()' or 'rxtractogon()' to "tidy"" long-format:

• 'tidy_grid(response)`

For data requests that cross the dateline for datasets that are on a (-180, 180) longitude grid, there are some important caveats:

• Request must be on a (0, 360) longitude grid
• Several of the checks that the request makes sense are disabled if the request cross the dateline and the dataset is on a (-180, 180) longitude grid.
• User therefore has more responsibility to check that the request makes sense for the dataset being accessed.

rerddapXtracto uses the rerddap, ncdf4 , parsedate, plotdap and sp packages , and these packages (and the packages imported by these packages) must be installed first or rerddapXtracto will fail to install.

install.packages("ncdf4") 
install.packages("parsedate") 
install.packages("plotdap") 
install.packages("rerddap") 
install.packages("sp")

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