Re: limit on coordinate?

[Bertrand REPTIN <reptin@xxxxxxxxxxxxxx>]

Steve Hankin wrote:
> 
> 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.
> 


Hello Steve,

Unfortunately, I read an ascii file containing 73403 values of water
depth with irregular and **unevenly spaced** values of latitude and
longitude, in the form :

lat	lon	depth
46.6396  -4.9982 1348.0   ! value 1
...
45.5245  -3.1742  149.0	! value 73403


I read them as follows :

yes? define axis/t=1:73403:1 taxis
yes? define grid/t=taxis tgrid
yes? file/var="lat,lon,prof"/grid=tgrid bathyzoe1
yes? plot/vs lon,lat
yes? sh data
     currently SET data sets:
    1> ./bathyzoe1  (default)
 name     title                             I         J        
K         L
 LAT      LAT                              1:1       1:1       1:1      
1:73403
 LON      LON                              1:1       1:1       1:1      
1:73403
 PROF     PROF                             1:1       1:1       1:1      
1:73403

This plotting was OK, although the number of points was too big !

but not the following one, to transform data in a regular grid :

yes? go objective lon lat prof "-5:-3:0.01" "45:47:0.01" 0 1
Your result will be variable "gridded" in data set fer_objective.unf.
 **ERROR: a program limit has been reached: too many input points -
limit 50000
USER/COMMAND=OBJECTIVE/opt1=-5:-3:0.01,45:47:0.01,0,1/file=fer_objective.unf
lon/10000,lat/10000,prof
Command file, command group, or REPEAT execution aborted

This last command is OK if I use file/skip=30000 to have less than 50000
values

How can I easily transform the 73403 irregular (x,y,z) values to a 2D
regular grid ?

Thanks

Bertrand


*******************************************************************************
Bertrand REPTIN
STSN/GESMA - BP42 - BREST naval - FRANCE
Tel. 98-22-53-67
Fax. 98-22-72-13
e-mail :  reptin@gesma.fr
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