Re: [netcdfgroup] netcdf4 compound types and deflation

• To: Nick.Johnson@xxxxxxxx
• Subject: Re: [netcdfgroup] netcdf4 compound types and deflation
• From: Russ Rew <russ@xxxxxxxxxxxxxxxx>
• Date: Fri, 03 Feb 2012 21:56:06 -0700

Hi Nick,

> I wanted to try some compression on a dataset whilst converting to netcdf4/hd
> f5 to see if we can save some space.
> 
> I have my compound type defined as such:
> 
> if (nc_def_compound(grp2id, sizeof(struct elements), "sample_elements", &type
> id))
>      ERR(retval);
> if (nc_insert_compound(grp2id, typeid, "elem", offsetof(struct elements, elem
> ), NC_INT64))
>      ERR(retval);
> if (nc_insert_compound(grp2id, typeid, "type", offsetof(struct elements, type
> ), NC_INT))
>      ERR(retval);
> if (nc_insert_compound(grp2id, typeid, "x", offsetof(struct elements, x), NC_
> INT))
>      ERR(retval);
> if (nc_insert_compound(grp2id, typeid, "y", offsetof(struct elements, y), NC_
> INT))
>      ERR(retval);
> if (nc_insert_compound(grp2id, typeid, "z", offsetof(struct elements, z), NC_
> INT))
>      ERR(retval);
> 
> 
> and then I call:
> if ((retval = nc_def_var(grp2id, "data", typeid, 2, dimids, &varid2)))
>      ERR(retval);
> 
> which works fine. If add in the following, before my call to nc_put_var:
> 
> if (retval = nc_def_var_deflate(ncid, varid2, 0, 1, 1))
>      ERR(retval)
> 
> I get the error:
> Error: NetCDF: Variable not found
> 
> which is odd as "varid2" is a legal variable id.

The problem is the "ncid", which refers to the root group, but you've
defined "varid2" within a different group, so you need to use:

 if (retval = nc_def_var_deflate(grp2id, varid2, 0, 1, 1))

--Russ

• References:
  • [netcdfgroup] netcdf4 compound types and deflation
    • From: Nick Johnson