netcdf4-python copying variables from one netcdf file to another

This has arisen as a problem of converting NETCDF4 to NETCDF3_CLASSIC which is still used by some old software. I did try nc4tonc3 provided with netCDF4 but that one also wanted the input file in NETCDF4_CLASSIC format... That is why I wrote this little script to actually copy variables and dimensions. There were no attributes in the files, so I did not care to handle attributes.

	# -*- coding: utf-8 -*-
	from netCDF4 import Dataset
	#input file
	dsin = Dataset("crop.nc")
	#output file
	dsout = Dataset("crop.nc3", "w", format="NETCDF3_CLASSIC")
	#Copy dimensions
	for dname, the_dim in dsin.dimensions.iteritems():
	print dname, len(the_dim)
	dsout.createDimension(dname, len(the_dim) if not the_dim.isunlimited() else None)
	# Copy variables
	for v_name, varin in dsin.variables.iteritems():
	outVar = dsout.createVariable(v_name, varin.datatype, varin.dimensions)
	print varin.datatype
	# Copy variable attributes
	outVar.setncatts({k: varin.getncattr(k) for k in varin.ncattrs()})
	outVar[:] = varin[:]
	# close the output file
	dsout.close()

view raw Converter.py hosted with ❤ by GitHub

From a comment by Nikolay Koldunov, there is a utility for this tasks nccopy ...