GetCDLData: Access CDL raster data

In cbw1243/cdlRotate: Access Cropland Data Layer Data and Analyze Land Use Changes in the United States

Description

A function that retrieves CDL raster data for any area of interests for a year.

Usage

GetCDLData(aoi = NULL, year = NULL, type = NULL, mat = FALSE, crs = NULL)

Arguments

aoi	Area of interest. Could be a county FIPS code, a coordinate with two numeric values, multiple coordinates (e.g, three coordinates that defines a triangle), or four values that defines a rectangle. The default coordinate system (used by CDL) is the Albers equal-area conic projection, or Albers projection. Users can provide coordinates from a different projection method, but user have to specify the coordinate system in the crs argument. For example, users can provide longitude/latitude coordinates here, while letting crs be '+init=epsg:4326'.
year	year of data to request. Can be a numerical value or a character.
type	type of aoi. 'f' for county, 'ps' for points, 'b' for box, 'p' for a single point.
mat	TRUE/FALSE. If FALSE (default), return a raster file; if TRUE, return a matrix that saves the data.
crs	projection system for the coordinate, such as '+init=epsg:4326' for longitude/latitude.

Value

The function returns a raster file or a matrix that saves the land use information. The file that links the category codes with the category names are available at~https://www.nass.usda.gov/Research_and_Science/Cropland/docs/cdl_codes_names.xlsx.

Examples

# Example 1. Retrieve data for the Champaign county in Illinois (FIPS = 17109) in 2018.
data <- GetCDLData(aoi = 17019, year = 2018, type = 'f')
raster::plot(data) # plot the data.

# Example 2. Retrieve data for a single point by long/lat in 2018.
data <- GetCDLData(aoi = c(-94.6754,42.1197), year = 2018, type = 'p', crs = '+init=epsg:4326')
data
# Below uses the same point, but under the default coordinate system
data <- GetCDLData(aoi = c(108777,2125055), year = 2018, type = 'p')
data

# Example 3. Retrieve data for a triangle defined by three coordinates in 2018.
data <- GetCDLData(aoi = c(175207,2219600,175207,2235525,213693,2219600), year = 2018, type = 'ps')
raster::plot(data)

# Example 4. Retrieve data for a rectangle box defined by three corner points in 2018.
data <- GetCDLData(aoi = c(130783,2203171,153923,2217961), year = '2018', type = 'b')
raster::plot(data)

cbw1243/cdlRotate documentation built on March 31, 2020, 12:58 a.m.