Re: virtual variable

[Zhangfan Xing <xing@xxxxxxxxxxxxxxxxxxxx>]

Now LAS says:

yes? cancel mode verify
yes? cancel mode interp
yes? canc data/all
yes? go diff "/mnt/lasdata0/datasets/adjoint/Have.1998.cdf" "1" "1"
"Have_h"
yes? set
region/x="180":"540"/y="-79.5":"78.5"/k=1/t="06-Jan-1998":"06-Jan-1998"
yes? set win/size=.5
yes? set win/asp=0.658333333333333
yes? GO "/tmp/lasgo109947067668.jnl"
 **ERROR: variable unknown or not in data set: HAVE_F
CONTOUR/FILL/levels=30/set Have_h
Command file, command group, or REPEAT execution aborted

I am not familiar with ferret.
Any cookbook thinner than the manual?

Thanks,

Zhangfan


On Thu, 23 Aug 2001, Joe Sirott wrote:

> You have to define URLs for every variable (even generated variables) if a URL isn't defined at the dataset level. In your case, the following should work:
> 
> <Have_h units="meters" name="diff" url="file:/mnt/lasdata0/datasets/adjoint/Have.1998.cdf#Have_h">
> ...
> 
> Zhangfan Xing wrote:
> 
> > Hi,
> >
> > I am trying to set up a virtual variable
> > following instructions in
> > http://ferret.wrc.noaa.gov/Ferret/LAS/FAQ/virtual_variables.html
> >
> > However, LAS complains about:
> >
> > No 'url' attribute specified for 'var' element at Ferret.pl line 82
> >
> > The URLs are in fact specified in *.xml for real variables.
> >
> > Any more detailed docs about this topic other than FAQ?
> >
> > Attached please find relevant part of my *.xml file and ferret script
> > that defines the virtual variable.
> >
> > Thanks in advance.
> >
> > Zhangfan
> >
> > ---------------- part of *.xml -----------------
> >         <Have_e units="meters" name="Sea Surface Height 1997"
> > url="file:/mnt/lasdata0/datasets/adjoint/Have.1997.cdf#Have">
> >          <link match="/lasdata/grids/jpl_2d_grid_1997"/>
> >         </Have_e>
> >
> >         <Have_f units="meters" name="Sea Surface Height 1998"
> > url="file:/mnt/lasdata0/datasets/adjoint/Have.1998.cdf#Have">
> >          <link match="/lasdata/grids/jpl_2d_grid_1998"/>
> >         </Have_f>
> >
> >         <Have_h units="meters" name="diff">
> >          <link match="/lasdata/grids/jpl_2d_grid_1998"/>
> >           <properties>
> >            <ferret>
> >             <init_script>diff</init_script>
> >            </ferret>
> >           </properties>
> >         </Have_h>
> >
> > ----------------- ferret script ./jnls/diff.jnl -------------
> >
> > let/title="Difference"/units="maters" Have_h = Have_e - Have_f
> 
> --
> Joe Sirott
> 
> 
>