CFAuxiliaryLongLat {ncdfCF} | R Documentation |
CF auxiliary longitude-latitude variable
Description
This class represents the longitude and latitude variables that compose auxiliary coordinate variable axes for X-Y grids that are not longitude-latitude.
The class provides access to the data arrays for longitude and latitude from the netCDF resource, as well as all the details that have been associated with both axes. Additionally, this class can generate the index to extract values on a long-lat grid of the associated X-Y grid data variable using a user-selectable extent and resolution.
Auxiliary longitude-latitude grids are only supported for reading from a netCDF resource. Creating an instance manually therefore has no practical purpose.
Super class
ncdfCF::CFObject
-> CFAuxiliaryLongLat
Public fields
varLong
The NCVariable instance of the longitude values.
varLat
The NCVariable instance of the latitude values.
boundsLong
The CFBounds instance for the longitude values of the grid.
boundsLat
The CFBounds instance for the latitude values of the grid.
axis_order
Either
c("X", "Y")
(default) orc("Y", "X")
to indicate the orientation of the latitude and longitude grids.
Active bindings
friendlyClassName
(read-only) A nice description of the class.
name
(read-only) The name of the auxiliary lon-lat grid.
aoi
Set or retrieve the AOI for the long-lat grid.
lon
(read-only) Retrieve the longitude grid.
lat
(read-only) Retrieve the latitude grid.
extent
(read-only) Retrieve the extent of the longitude and latitude grids, including bounds if they have been set. The extent is reported as a numeric vector of the four elements minumum and maximum longitude and minimum and maximum latitude.
dim
(read-only) The dimensions of the longitude and latitude grids.
dimids
(read-only) The dimids of the longitude and latitude grids.
Methods
Public methods
Inherited methods
Method new()
Creating a new instance. It should normally not be useful to create an instance of this class other than upon reading a netCDF resource.
Usage
CFAuxiliaryLongLat$new(varLong, varLat, boundsLong, boundsLat)
Arguments
varLong, varLat
The NCVariable instances with the longitude and latitude grid values, respectively.
boundsLong, boundsLat
The bounds of the grid cells for the longitude and latitude, respectively, if set.
Method print()
Summary of the auxiliary longitude-latitude variable printed to the console.
Usage
CFAuxiliaryLongLat$print()
Method brief()
Some details of the auxiliary longitude-latitude grid.
Usage
CFAuxiliaryLongLat$brief()
Returns
A 2-row data.frame
with some details of the grid components.
Method sample_index()
Return the indexes into the X (longitude) and Y (latitude) axes of the original data grid of the points closest to the supplied longitudes and latitudes, up to a maximum distance.
Usage
CFAuxiliaryLongLat$sample_index(x, y, maxDist = NULL)
Arguments
x, y
Vectors of longitude and latitude values in decimal degrees, respectively.
maxDist
Numeric value in decimal degrees of the maximum distance between the sampling point and the closest grid cell. If omitted (default), the distance is calculated from the nominal resolution of the grids.
Returns
A matrix with two columns X
and Y
and as many rows as
arguments x
and y
. The X
and Y
columns give the index into the
grid of the sampling points, or c(NA, NA)
is no grid point is located
within the maxDist
distance from the sampling point.
Method grid_index()
Compute the indices for the AOI into the data grid.
Usage
CFAuxiliaryLongLat$grid_index()
Returns
An integer matrix with the dimensions of the AOI, where each grid cell gives the linear index value into the longitude and latitude grids.
Method clear_cache()
Clears the cache of pre-computed grid index values if an AOI has been set.
Usage
CFAuxiliaryLongLat$clear_cache(full = FALSE)
Arguments
full
Logical (default =
FALSE
) that indicates if longitude and latitude grid arrays should be cleared as well to save space. These will then be re-read from file if a new AOI is set.
Method clone()
The objects of this class are cloneable with this method.
Usage
CFAuxiliaryLongLat$clone(deep = FALSE)
Arguments
deep
Whether to make a deep clone.