Re: limit on coordinate?

[hankin@xxxxxxxxxxxxxxxxxxx (Steve Hankin)]

Hi Dongxiao,

Yes, Ferret does have a limit of 50,000 coordinate points but it need not get
in your way. It is only really a limit if you have 50K **unevenly spaced**
coordinate points -- this is rarely the case.

Your NetCDF file needs to TELL Ferret that the time points are regularly
spaced. Ferret is attempting to read them so it can check the spacing. Having
determined that the points were evenly spaced it would retain only the start,
end, and delta values (freeing up the space), but it isn't getting that far.

In the Ferret Users Guide (http://tmap.pmel.noaa.gov/home/ferret/ug/v44/) you
will find a short discussion of this under:

	Chapter 9: CONVERTING TO NetCDF
		3.5.4 Evenly spaced coordinates (long axes)

At the end of this message I will paste the text from the users guide and
a message that explains an easy way to modify your NetCDF file.

	- steve

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

On May 22,  2:23pm, Dongxiao Zhang wrote:
> Subject: limit on coordinate?
> Hi all,
>
> Does FERRET have limitation on storage for coordinate? I have a netCDF
> file containing a time series with 35088 time levels. When I tried to use
> FERRET, use metero.cdf, I got " **TMAP ERR: limit on storage for
> coordinates has been reached   MAX= 50000".  Then I made a test by cutting
> the data down to 5000 time levels, FERRET is OK to work on this short time
> series.
>
> Can somebody tell me how to go around this problem?
>
> Thanks,
>
> Dongxiao
>
> --------------------------------------------------------------------
> Dongxiao Zhang
> Division of Meteorology and Physical Oceanography
> Rosenstiel School of Marine and Atmospheric Science
> 4600 Rickenbacker Causeway
> Miami, FL 33149
> Phone  : (305)361-4806
> Fax    : (305)361-4696
> Office : MSC Room 309
> --------------------------------------------------------------------
>
>-- End of excerpt from Dongxiao Zhang

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

	Chapter 9: CONVERTING TO NetCDF
		3.5.4 Evenly spaced coordinates (long axes)

	(http://tmap.pmel.noaa.gov/home/ferret/ug/v44/)


	3.5.4 Evenly spaced coordinates (long axes)

	If the coordinate axes are evenly spaced, the attribute
	"point spacing" should be used:


		slat: point_spacing = "even" ;

	When used, this attribute will improve memory use efficiency in Ferret.
	This is especially important for very large axes--10,000 points or
	more.

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

On Dec 8,  9:20am, Steve Hankin wrote:
> Subject: point_spacing="even"
> Hi Bruce,
>
> I mentioned a single command way to add an attribute to a netCDF file.  This
> will take your computer a few minutes ... but it won't take much time for
you!
>
> To add     TEMP:point_spacing = "even" ;   :
>
> % ncdump temp.cdf | sed -e '/TEMP:units/a\\
>                 TEMP:point_spacing = "even" ;'  | ncgen -o new_temp.cdf
>