[gradsusr] Utilizing data from text file to make calculation in GrADS

[Phil Klotzbach]

Chuck and Ricardo,

Thanks for the rapid responses.  I used the "say" command in GrADS to 
confirm that pointlon, pointlat and pointtime variables are all reading 
what I want them to, so I don't think the substr vs. sublin function is 
an issue.  Thanks for the suggestion about clearing up the extra single 
quotes.  Unfortunately, modifying the code did not change the result.  
It seems like GrADS is still treating those variables as if they are 
text strings instead of numbers.

Phil

----------------------------------------------------
Phil Klotzbach, Ph.D.
Research Scientist
Department of Atmospheric Science
Colorado State University
Email: philk at atmos.colostate.edu
----------------------------------------------------

On 2/22/2013 6:49 AM, Charles Seman - NOAA Federal wrote:
> Phil,
>
>   From http://grads.iges.org/grads/gadoc/script.html#intrinsic
> ---
> read (filename)
> This functions reads individual records from file filename. Repeated
> calls must be made to read consecutive records. The result is a string
> containing two lines: the first line is the return code, the 2nd line is
> the record read from the file. The record may be a maximum of 80
> characters. Use the sublin function to separate the result. Return codes
> are:
>
>       0 - ok
>       1 - open error
>       2 - end of file
>       8 - file open for write
>       9 - I/O error
>
> Files are opened when the first call to read is made for a particular
> file name. Files are closed when the execution of the script file
> terminates (note that files remain open between function calls, etc).
> ---
>
> Try something like this in your script:
> ...
> res = read(input)
> rc = sublin(res,1)
> if ( rc != 0 )
>     say 'return code is: 'rc
>     exit
> endif
> rec = sublin(res,2)
> ...
>
> also, check on "looptime" vs "time" for loop counter...
>
> Hope this helps,
> Chuck
>
>
> On 02/21/2013 01:03 PM, Phil Klotzbach wrote:
>> Hi everyone,
>>
>> I am currently running GrADS 2.0.1 on my Windows 7 laptop.  What I have
>> is a simple text file with three columns, a longitude, a latitude, and a
>> time (since 1979 at 0Z).  When I attempt to run the code in GrADS, I get
>> the following error message:
>>
>> Set error: Missing or invalid arguments for LON option
>> Non-numeric args to numeric operations
>> Error occurred on line 18
>> In file /cygdrive/c/OPENGR~1/Contents/Resources/Scripts/readfile.gs
>>
>> The strange thing is, I can check and see that latitude has been set
>> correctly by GrADS.  It just has problems with longitude and time. I
>> used the three say commands to verify that it has read in the variables
>> correctly (which it has).
>>
>> The following is my code as currently written:
>>
>> input = 'c:\test.txt'
>> 'open c:\500mbtemp.ctl'
>> looptime = 1
>> while (looptime < 3)
>> rec = read(input)
>> pointlon = substr(rec, 2, 7)
>> pointlat = substr(rec, 10, 7)
>> pointtime = substr(rec, 17, 2)
>> say pointlon
>> say pointlat
>> say pointtime
>> 'set lat 'pointlat''
>> 'set lon 'pointlon''
>> 'set t 'pointtime''
>> 'd temp'
>> answer=result
>> res=write("c:\500mbtemp.txt",answer)
>> time=time+1
>> endwhile
>>
>> Here are the contents of c:\test.txt
>>
>> 150.00 -16.75 5
>> 149.25 -22.50 7
>>
>> Lastly c:\500mbtemp.ctl is an ERA-Interim 500 mb temperature file. I
>> have verified manually that the file opened correctly and is working
>> properly.   I know the GrADS treats all variables read from text files
>> as strings, and I'm guessing that this is what is causing the problem
>> here.  Any insights into how this problem can be solved are much
>> appreciated!  Thanks!
>>
>> Phil
>>