[gradsusr] North Arrow

[Jeff Duda]

As far as I know there is no script in the library to do this, so you will
have to do it manually.

-North arrow: Draw it using "draw poly" or there is likely a font #3
specification of an arrow in the Grads fonts library. I'm not sure which
hotkey it is, but if you run fonts.gs it will print out a map that you can
use to determine that. In the code you would say
'set font 3'
'draw string XXX YYY ((()))' [whatever the key is for the arrow]

-As for the scale, hopefully you know the grid spacing of the data. You can
use the 'q pos' and 'q xy2w' functions to query some known points (with a
known distance) on your map and then use the great circle distance formula
to calculate the distance. You can also use 'q gr2xy' using grid index
points instead of world coordinates to know how long of a bar to draw
corresponding to a known N*dx.

Jeff Duda

On Thu, Mar 7, 2019 at 12:29 AM Joe Nayo <nayojoee at gmail.com> wrote:

> Dear GrADS Users,
>
> Is there a way of displaying a north arrow and scale on a map?
>
> Any help will be appreciated,
> Joe.
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-- 
Jeff Duda, Research Scientist
University of Colorado Boulder
Cooperative Institute for Research in Environmental Sciences
NOAA/OAR/ESRL/Global Systems Division
Boulder, CO
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