copy netcdf file using python

Question

I would like to make a copy of netcdf file using Python.

There are very nice examples of how to read or write netcdf-file, but perhaps there is also a good way how to make the input and then output of the variables to another file.

A good-simple method would be nice, in order to get the dimensions and dimension variables to the output file with the lowest cost.

Answer 1

I found the answer to this question at python netcdf: making a copy of all variables and attributes but one, but I needed to change it to work with my version of python/netCDF4 (Python 2.7.6/1.0.4). If you needed to add or subtract elements, you would make the appropriate modifications.

import netCDF4 as nc

def create_file_from_source(src_file, trg_file):
    src = nc.Dataset(src_file)
    trg = nc.Dataset(trg_file, mode='w')

    # Create the dimensions of the file
    for name, dim in src.dimensions.items():
        trg.createDimension(name, len(dim) if not dim.isunlimited() else None)

    # Copy the global attributes
    trg.setncatts({a:src.getncattr(a) for a in src.ncattrs()})

    # Create the variables in the file
    for name, var in src.variables.items():
        trg.createVariable(name, var.dtype, var.dimensions)

        # Copy the variable attributes
        trg.variables[name].setncatts({a:var.getncattr(a) for a in var.ncattrs()})

        # Copy the variables values (as 'f4' eventually)
        trg.variables[name][:] = src.variables[name][:]

    # Save the file
    trg.close()

create_file_from_source('in.nc', 'out.nc')

This snippet has been tested.