psbar {gmt} | R Documentation |
Call GMT to add bars to the active map and save in postscript format. This function does the necessary calculations to render bars in standard height given a Mercator-projected map. It is not intended for other projections.
psbar(x, cmd="-JM -R -W1p -G180 -O -K", file=options("gmt.file"), ref=0, digits=options("digits"))
x |
data frame, matrix, or filename containing the data to be plotted. |
cmd |
string of arguments passed to psxy . |
file |
filename where the map is saved. |
ref |
reference latitude where Height=1 renders a bar 1 degree high. |
digits |
precision used when rounding the geographic coordinates. |
The data are arranged in four columns: Lon, Lat, Width, and Height, in
that order. See help(r2gmt)
for valid data file format when
argument x
is a filename. See the GMT documentation for details
on psxy
and other GMT commands.
Null, but the map is annotated and saved in postscript format.
As a side product, a temporary file ‘lastBAR.gmt’ is saved in the
working directory.
Assumes that GMT version 4 is installed, i.e. that psxy
and
other commands are in the path, and environment variable GMTHOME
is defined.
The derivative of the Mercator projection is used to standardize the bar height:
f'(N) = 1 / (2 * tan(pi/4+N/2) * cos(pi/4+N/2)^2)
where N is latitude in radians and f(N) is the y-axis coordinate. The bar height at a given latitude is h*f'(ref)/f'(N), where h is the height passed by the user and ref is a reference latitude where h=1 renders a bar 1 degree high.
Arni Magnusson arnima@u.washington.edu.
gmt-package
gives an overview of the package.
## Not run: gmt(demo.par) pscoast(demo.coast) psxy(demo.xy) pstext(demo.text) psbar(demo.bar, ref=64) psclose() ## End(Not run)