Re: [ferret_users] Picking the time corresponding to maximum value of a variable from an nc file

[Hein Zelle <hein.zelle@xxxxxxxxxxxxx>]

Dear Sandhya,

> I have done exactly what you said, though I did not understand why you are doing 
> ! limit to one point only
> ?set region /i=100/j=50

This is because the backticks need to resolve to a single value.  If
you do this across a whole 2-dimensional grid like I did (i.e. SST
values over a full year), you may get different time indices for each
grid point where the maximum occurs.

So, this is still a valid expression which you can plot

sst[t=@max]

as well as

zero_at_max[t=@loc:0.0]

but you can't put that between backticks, as it's a whole grid of
values, not a single one.   I was setting the i and j region to reduce
my data to a single number.

> yes? let zero_at_max=hs[t=@max]-hs
> yes? let maxtval=zero_at_max[t=@loc:0.0] 
> yes? set region/i=100/j=50
> yes? let dummy=t[gt=hs,t=`maxtval`]
>  !-> DEFINE VARIABLE dummy=t[gt=hs,t=954690]
> yes? let tstring=`dummy,return=tend`
>  !-> DEFINE VARIABLE tstring=12-DEC-2009 17:57:00
>  **ERROR: command syntax: 12-DEC-2009 17:57:00
>           illegal character: :

Ah, sorry, I didn't test the code verbatim.  You need double quotes to
assign the result to a variable:

  let tstring="`dummy,return=tend`"

Otherwise you're telling ferret (see the output)

  let tstring=12-DEC-2009 17:57:00

which is a syntax error because there's a space in the string, and
there's no quotes.

Kind regards,
     Hein



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Dr. Hein Zelle
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