geoknife package version 1.0.0

Build status Build Status Coverage Status Tools for geo-web processing of gridded data via the Geo Data Portal. geoknife slices up gridded data according to overlap with irregular features, such as watersheds, lakes, points, etc. The result is subsetted data in plain text, NetCDF, geotiff or other formats.


Installing geoknife

To install the stable version of geoknife package with dependencies:

    repos = c("",""),
    dependencies = TRUE)

Or to install the current development version of the package:


geoknife overview

The geoknife package was created to support web-based geoprocessing of large gridded datasets according to their overlap with landscape (or aquatic/ocean) features that are often irregularly shaped. geoknife creates data access and subsequent geoprocessing requests for the USGS's Geo Data Portal to carry out on a web server. The results of these requests are available for download after the processes have been completed. This type of workflow has three main advantages: 1) it allows the user to avoid downloading large datasets, 2) it avoids reinventing the wheel for the creation and optimization of complex geoprocessing algorithms, and 3) computing resources are dedicated elsewhere, so geoknife operations do not have much of an impact on a local computer.

geoknife interacts with a remote server to figure out what types of processing capabilities are available, in addition to seeing what types of geospatial features are already available to be used as an area of interest (commonly, these are user-uploaded shapefiles). Because communication with web resources are central to geoknife operations, users must have an active internet connection.

The main elements of setting up and carrying out a geoknife 'job' (geojob) include defining the feature of interest (the stencil argument in the geoknife function), the gridded web dataset to be processed (the fabric argument in the geoknife function), and the the processing algorithm parameters (the knife argument in the geoknife function). The status of the geojob can be checked with check, and output can be loaded into a data.frame with result.

What can geoknife do?

define a stencil that represents the geographic region to slice out of the data
# from a single point
stencil <- simplegeom(c(-89, 46.23))
   # -- or --
# from a collection of named points
stencil <- simplegeom(data.frame(
              'point1' = c(-89, 46), 
              'point2' = c(-88.6, 45.2)))
   # -- or --
#for a state from a web available dataset
stencil <- webgeom('state::New Hampshire')
stencil <- webgeom('state::New Hampshire,Wisconsin,Alabama')
   # -- or --
#for HUC8s from a web available dataset
stencil <- webgeom('HUC8::09020306,14060009')
define a fabric that represents the underlying data
# from the prism dataset:
fabric <- webdata('prism')
   # -- or --
# explicitly define webdata from a list:
fabric <- webdata(list(
            times = as.POSIXct(c('1895-01-01','1899-01-01')),
            url = '',
            variables = 'ppt'))
# modify the times field:
times(fabric) <- as.POSIXct(c('1990-01-01','2005-01-01'))
create the processing job that will carry out the subsetting/summarization task
job <- geoknife(stencil, fabric, wait = TRUE)

# use existing convienence functions to check on the job:
## $status
## [1] "Process successful"
## $URL
## [1] ""
## $statusType
## [1] "ProcessSucceeded"

see also:

plot the results
data <- result(job)
plot(data[,1:2], ylab = variables(fabric))
use an email to listen for process completion
job <- geoknife(webgeom('state::New Hampshire'), fabric = 'prism', email = '')

geoknife Functions (as of v0.12.1)

Function Title
geoknife slice up gridded data according to overlap with feature(s)
algorithm the algorithm of a webprocess
attribute the attribute of an webgeom
check check status of geojob
download download the results of a geojob
error convenience function for state of geojob
running convenience function for state of geojob
successful convenience function for state of geojob
start start a geojob
cancel cancel a geojob
geom the geom of a webgeom
inputs the inputs of a webprocess
id the process id of a geojob
values the values of a webgeom
result load the output of a completed geojob into data.frame
variables the variables for a webdata object
times the times of a webdata object
url the url of a webdata, webgeom, geojob, or webprocess
version the version of a webgeom or webdata
xml the xml of a geojob
query query datasets or variables

geoknife classes (as of v0.12.0)

Class Title
simplegeom a simple geometric class. Extends sp::SpatialPolygons
webgeom a web feature service geometry
webprocess a web processing service
webdata web data
geojob a geo data portal processing job
datagroup a simple class that contains data lists that can be webdata

What libraries does geoknife need?

This version requires httr, jsonlite, and XML. All of these packages are available on CRAN, and will be installed automatically when using the install.packages() instructions above.


This software is in the public domain because it contains materials that originally came from the U.S. Geological Survey, an agency of the United States Department of Interior. For more information, see the official USGS copyright policy

Although this software program has been used by the U.S. Geological Survey (USGS), no warranty, expressed or implied, is made by the USGS or the U.S. Government as to the accuracy and functioning of the program and related program material nor shall the fact of distribution constitute any such warranty, and no responsibility is assumed by the USGS in connection therewith.

This software is provided "AS IS."