[gradsusr] GrADS convert longitude west to east

Fri Jul 13 10:11:38 EDT 2018

Hi Tracey,

That’s getting into the difference in a grads script variable and variables used on command line and such.  Anything you put in quotes would be something you could type into a Grads command line session.

If you modify your script like:

lonmine = 360 - lonmin
lonmaxe = 360 - lonmax
say lonmine
say lonmaxe

It should work.

Colleen

On Jul 12, 2018, at 1:08 PM, Tracey <tdorian10 at gmail.com<mailto:tdorian10 at gmail.com>> wrote:

Hi Bill,

Thanks for your response!  I'm still a little bit confused though.  I am passing into the script a grid, for example:

grads -lc "script.gs<http://script.gs/> 25 50 -130 -60"

Where 25 and 50 are latmin and latmax, and -130 and -60 are lonmin and lonmax.  It is necesary in my GrADS script to use both degrees east and degrees west longitude.

So in my GrADS script, is there a way to just do something like the following in the bold red color?

function main(arg)
latmin=subwrd(arg,1)
latmax=subwrd(arg,2)
lonmin=subwrd(arg,3)
lonmax=subwrd(arg,4)
....
'set lat 'latmin' 'latmax
'set lon 'lonmin' 'lonmax
'define lonmine = 360 - 'lonmin
'define lonmaxe = 360 - 'lonmax
say lonmine
say lonmaxe

The above in red doesn't seem to work and I'm not sure why.  Maybe I have quotations in the wrong places?

Thanks,
Tracey

On Thu, Jul 12, 2018 at 7:39 AM, Bill Bua - NOAA Affiliate <bill.bua at noaa.gov<mailto:bill.bua at noaa.gov>> wrote:
Hi Tracey --

There's a difference between a script variable and what I believe is called an intrinsic variable, in GrADS. With script variables, you would indeed use "define".  But for intrinsic variables (and this from my experience needs to be in a script), I believe you'd have to pull the values from a string of display-ed data.  That is:

"d lon"
lonw = subwrd(result,<leftmost character position>, <rightmost character position>)

where leftmost and rightmost refer to the left and right position in the line that includes the variable lonw.
If there are multiple lines in the display, you'll have to first choose the line that contains the longitude. If it were the 2nd line, you'd have the command

lonline=sublin(result, 2)
then do subwrd(lonline, <leftmost>,<rightmost>) as above.

Finally, you'd define your lone = 360 - lonw ("define lone = 360 - lonw").

I'm doing this from memory ... it's been awhile since I wrote a script. I'll check it out once I'm where I can write a test script and see if this works.

Bill

Dr. William R. (Bill) Bua
UCAR/COMET/NCEP/EMC
5830 University Research Court #2784
College Park, MD 20740

On Wed, Jul 11, 2018 at 6:49 PM, Tracey <tdorian10 at gmail.com<mailto:tdorian10 at gmail.com>> wrote:
Hi Bill,

Thanks, how would I use this arithmetic in the GrADS script with 'lonmax' and 'lonmin' arguments?  This is what I'm having trouble with.   Would I use "define"?

Sincerely,
Tracey

On Wed, Jul 11, 2018 at 6:31 PM, Bill Reilly <bill_reilly at compuserve.com<mailto:bill_reilly at compuserve.com>> wrote:
360 - degW = degE

--

Bill Reilly

(+34) 686-110-748

bill at passageweather.com<mailto:bill at passageweather.com>
www.passageweather.com<http://www.passageweather.com/>

bill at brwebworks.com<mailto:bill at brwebworks.com>
www.brwebworks.com<http://www.brwebworks.com/>

On 12/07/2018 00:14, Tracey wrote:
Hi GrADS users,

Is there a GrADS function or script that converts degrees west longitude into degrees east?  For example, if I input "lonmin" and "lonmax" arguments into a GrADS script and I wanted to convert those longitudes from degrees west to degrees east within the script by defining new "lonmin" and "lonmax" variables?

Thanks in advance for any help,
Tracey

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