Various utilities functions for AURELHY
Description
These functions manipulate geographical coordinates in various ways to optimize computation of the AURELHY method.
Usage
1 2 3 4 5 6 7 8 9 10  deg.lat(latitude)
deg.lon(latitude)
polar.coords(geomat, x, y, maxdist)
match.coords(points, table, tol = 0.002)
coords(x, ...)
resample(x, ...)
add.points(x, ...)
## S3 method for class 'geomask'
add.points(x, geopoints, ...)
dist2sea(geotm)

Arguments
latitude 
the latitude in decimal degrees 
geomat 
a 'geomat' object 
x 
X coordinate of the reference point for 
y 
Y coordinate of the reference point 
maxdist 
maximum distance to consider in km. All points whose distance from the reference point is larger are not considered in the calculation 
points 
a list or data frame with X and Y coordinates of the points to match to the reference points (in decimal degrees, for instance) 
table 
a similar list or data frame with X(ref) and Y(ref) coordinates
of the reference points to be matched (in the same units as for

tol 
the maximum tolerance in X and Y units to consider points are matching, that is, X +/ tol = X(ref) and Y +/ tol = Y(ref) 
... 
further arguments passed to the method 
geopoints 
a geopoints object from which we want to add corresponding points in a geomask 
geotm 
a geotm object 
Details
deg.lat()
and deg.lon()
provide the length of one degree in,
respectively, latitude and longitude in km, given the corresponding latitude
in decimal degrees. The ellipsoid defined in WGS84 model is used for these
calculations.
polar.coords()
calculates polar coordinates of points.
match.coords()
selects points with matching coordinates, given a
tolerance distance between the reference points (i.e., from a geotm grid,
using coords(my_geotm, "xy")
) and the points to match (stations).
coords()
is a generic function that extracts geographical coordinates
from one object in different fashions.
resample
is a generic function to resample a grid ('geomat' object).
add.points
add points from a geopoints object in a geomask.
dist2sea()
calculate the distance of points in a geotm object to the
sea.
Value
deg.lat()
and deg.lon()
return the length of one degree in km.
polar.coords()
returns a data frame with 'angle' in rad and 'dist'(ance)
in km for the reference point to each point in the grid, within 'maxdist'.
There is also a 'geomat' attribute containing the window of the initial
'geomat' object containing the considered points.
match.coords()
returns a vector of logical of the same length as the
number of colunms in the points data frame (that must contain 'x' and 'y'
columns with coordinates of points to be matched).
Author(s)
Philippe Grosjean <phgrosjean@sciviews.org>, and Francois Delobel for
dist2sea()
See Also
geomat
, auremask
Examples
1 2 3 4 5 