Re: How to extract length of axis to a symbol?

[Steve Hankin <hankin@xxxxxxxxxxxxx>]

Hi Mike,

If I am understanding you correctly, what you are after is to know what the time
index range becomes for a slug of data *after* it is regridded.

It is easy to find the date range (as opposed to index range) and use it as
follows:

     define symbol tstart `U_COMPONENT,return=tstart`
     define symbol tend `U_COMPONENT,return=tend`
     SAVE/FILE="m1_adcp.nc"/APPEND U_VEL_COMP[L="$TSTART":"$TEND"]

The date range after regridding will in some cases be smaller than before
regridding, since linear interpolation is not possible at the endpoints of the
source data. However, if the date ranges of the files that you are appending are
non-overlapping, I think the above procedure should work 100%.

    - steve

=====================================

"McCann, Mike" wrote:

> Andrew, Ansley, et al.-
>
> Thanks!   That define works.  Now I need a little help
> getting the index range of a regridded variable.  The
> first section below writes a new netCDF file and then
> I want to append to it with additional data, yet unless
> I specify the index range the first set of data gets
> overwritten by the no_data values from the 2nd set of data.
>
> LET V_VEL_COMP = V3[gt=TNEW@LIN]
> SAVE/FILE="m1_adcp.nc"/LLIMITS=1:($NTIME)/CLOBBER U_VEL_COMP,V_VEL_COMP
>
> USE
> "/hosts/tornado/vol/vol0/oasis/deployments/m1/199606/m1/netcdf/m1_adcp_19960
> 110_NarrowBand.nc"
> LET U1 = missing(U_COMPONENT_FLAG, -9999)
> LET U2 = IF U1 EQ 0 THEN 1
> LET U3 = U_COMPONENT * U2
> LET U_VEL_COMP = U3[gt=TNEW@LIN]
> LET V1 = missing(V_COMPONENT_FLAG, -9999)
> LET V2 = IF V1 EQ 0 THEN 1
> LET V3 = V_COMPONENT * V2
> LET V_VEL_COMP = V3[gt=TNEW@LIN]
>
> (How do I get the $LSTART & $LEND values that are needed for this?)
>
> SAVE/FILE="m1_adcp.nc"/APPEND
> U_VEL_COMP[L=$LSTART:$LEND],V_VEL_COMP[L=$LSTART:$LEND]
>
> Again, thanks in advance,
> Mike
>
> --
> Mike McCann   (mccann@mbari.org)
> Group Leader, Information Applications Group
> Monterey Bay Aquarium Research Institute
> 7700 Sandholdt Road
> Moss Landing, CA 95039-9644
> Voice: (831) 775-1769   Fax: (831) 775-1646 http://www.mbari.org/rd/iag.htm
>
> > -----Original Message-----
> > From: Andrew Wittenberg [mailto:andyw@splash.Princeton.EDU]
> > Sent: Tuesday, April 03, 2001 2:58 PM
> > To: McCann, Mike
> > Cc: ferret_users
> > Subject: Re: How to extract length of axis to a symbol?
> >
> >
> > On Tue, 3 Apr 2001, McCann, Mike wrote:
> >
> > > After defining an axis, e.g.:
> > >
> > > DEFINE AXIS/T=($TMIN):($TMAX):7200/UNITS=seconds TNEW
> > >
> > > How do I get the number of points in the axis and assign
> > > the number to a symbol?
> >
> > Hi Mike,
> >
> > Give this a try:
> >
> > yes? define symbol num_points `t[gt=tnew],r=lsize`
> > yes? say ($num_points)
> >
> > Andrew
> >
> > ----------------------------------------------------------------------
> > Andrew Wittenberg          Program in Atmospheric and Oceanic Sciences
> > andyw@splash.princeton.edu                        Princeton University
> > ----------------------------------------------------------------------
> >
> >

--

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