Re: [ferret_users] regridding transformation should reduce dimension . . .

[Ryo Furue <furue@xxxxxxxxxx>]

Hi all,

> Note that Z=@LOC doesn't mean "search from top to bottom for 10 degC."
>  Instead it means "search within the future evaluation context for 10
> degC."
>
> So when you later specify z10[k=1], @LOC dutifully searches only over
> k=1; and since 10degC isn't found in the top level, it evaluates to
> "missing."
>
> To insulate @LOC from future contexts, specify explicit z-limits:
[. . .]
> http://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/variables-xpressions/XPRESSIONS#_VPINDEXENTRY_528
>
> See also the following answer in the Ferret email archives:
>
> http://www.pmel.noaa.gov/maillists/tmap/ferret_users/fu_2006/msg00098.html
>
> which was found by searching the email archives for "missing context".

Thank you!  That's exactly solves my question.

So, couldn't we do something about it, so that this stuff becomes a
bit less confusing?  For example, what about this kind of extension?

   let z10 = temp[z=:@LOC:10]

Like Fortran, we could introduce a notation ":" to mean "the entire range".

Or, more radically(?), we could introduce a functionality of "evaluate
now", as when you SHADE or SAVE the variable, so that

   let z10 := temp[z=@LOC:10]  !<-- ":=" notation stolen from Makefile

would be equivalent to

   let z10 = temp[z=@LOC:10]
   save/file=tmp.nc z10
   cancel var z10
   use tmp.nc

Anyway, that was a very illuminating discussion to me!  Thank you folks!

Ryo