5.6 Copy Attribute from One NetCDF to Another: NF90_COPY_ATT

The function NF90_COPY_ATT copies an attribute from one open netCDF dataset to another. It can also be used to copy an attribute from one variable to another within the same netCDF dataset.

Usage

      function nf90_copy_att(ncid_in, varid_in, name, ncid_out, varid_out)
        integer,             intent( in) :: ncid_in,  varid_in
        character (len = *), intent( in) :: name
        integer,             intent( in) :: ncid_out, varid_out
        integer                          :: nf90_copy_att

ncid_in

The netCDF ID of an input netCDF dataset from which the attribute will be copied, from a previous call to NF90_OPEN or NF90_CREATE.

varid_in

ID of the variable in the input netCDF dataset from which the attribute will be copied, or NF90_GLOBAL for a global attribute.

name

Name of the attribute in the input netCDF dataset to be copied.

ncid_out

The netCDF ID of the output netCDF dataset to which the attribute will be copied, from a previous call to NF90_OPEN or NF90_CREATE. It is permissible for the input and output netCDF IDs to be the same. The output netCDF dataset should be in define mode if the attribute to be copied does not already exist for the target variable, or if it would cause an existing target attribute to grow.

varid_out

ID of the variable in the output netCDF dataset to which the attribute will be copied, or NF90_GLOBAL to copy to a global attribute.

Errors

NF90_COPY_ATT returns the value NF90_NOERR if no errors occurred. Otherwise, the returned status indicates an error. Possible causes of errors include:

• The input or output variable ID is invalid for the specified netCDF dataset.
• The specified attribute does not exist.
• The output netCDF is not in define mode and the attribute is new for the output dataset is larger than the existing attribute.
• The input or output netCDF ID does not refer to an open netCDF dataset.

Example

Here is an example using NF90_COPY_ATT to copy the variable attribute units from the variable rh in an existing netCDF dataset named foo.nc to the variable avgrh in another existing netCDF dataset named bar.nc, assuming that the variable avgrh already exists, but does not yet have a units attribute:

      use netcdf
      implicit none
      integer :: ncid1, ncid2, status
      integer :: RHVarID, avgRHVarID    ! Variable ID
      ...
      status = nf90_open("foo.nc", nf90_nowrite, ncid1)
      if (status /= nf90_noerr) call handle_err(status)
      status = nf90_open("bar.nc", nf90_write, ncid2)
      if (status /= nf90_noerr) call handle_err(status)
      ...
      ! Find the IDs of the variables
      status = nf90_inq_varid(ncid1, "rh", RHVarID)
      if (status /= nf90_noerr) call handle_err(status)
      status = nf90_inq_varid(ncid1, "avgrh", avgRHVarID)
      if (status /= nf90_noerr) call handle_err(status)
      ...
      status = nf90_redef(ncid2)   ! Enter define mode
      if (status /= nf90_noerr) call handle_err(status)
      ! Copy variable attribute from "rh" in file 1 to "avgrh" in file 1
      status = nf90_copy_att(ncid1, RHVarID, "units", ncid2, avgRHVarID)
      if (status /= nf90_noerr) call handle_err(status)
      status = nf90_enddef(ncid2)
      if (status /= nf90_noerr) call handle_err(status)