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[netCDF #RYL-581729]: the functions in 'netcdf.h'

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  • Subject: [netCDF #RYL-581729]: the functions in 'netcdf.h'
  • Date: Sat, 15 Dec 2018 13:15:43 -0700
The nc_get_var1 set of functions can be confusing because it
takes a single index no matter how many dimensions a variable has.

Let me suggest the following as perhaps more clear.
Suppose you want to read the value at position X,Y.
then define that position using:
> size_t start[2];
> start[0] = X;
> start[1] = Y;
Then ask for a single element using:
> size_t count[2];
> count[0] = 1;
> count[1] = 1;

Then do this:
> int zvalue; 
> nc_get_vara_int(ncid,zid,start,count,&zvalue)

where zid is the variable identifier for z that you
obtained using nc_inq_varid().



> 
> Recently, I tried to use 'netcdf.h', 'netcdf.dll' and 'netcdf.lib' to decode 
> the netcdf format file: the global topography data file 
> 'ETOPO1_Ice_g_gmt4.grd'(please see website: 
> https://www.ngdc.noaa.gov/mgg/global/relief/ETOPO1/data/ice_surface/grid_registered/netcdf/).
>  There are three variables in the file:  latitude named 'y', longitude named 
> 'x', and the topography data named 'z'. I used the function in 'netcdf.h' to 
> get the varid and vartype of 'z', which are 2 and 4(=NC_INT). And I tried to 
> use the function 'nc_get_var1_int' to get one value in 'z' with two 
> dimensions, however the function return -40. I don't know what happened. 
> Could you help me how to decode 'z' in the topography file 
> 'ETOPO1_Ice_g_gmt4.grd'  using the functions in  'netcdf.h'.
> 
> 
> Best regards.
> 
> Qu
> 

=Dennis Heimbigner
  Unidata


Ticket Details
===================
Ticket ID: RYL-581729
Department: Support netCDF
Priority: Critical
Status: Open
===================
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