ncfilter.py

A module that allows to create new netCDF files based on the information in an already existing one. Has a command-line interface.

The meta-information (everything except the actual data attached to the variables) is read into an internal data-structure in the class NcFilter. Methods of this class implement various operations on that meta-data. New actual data can be attached to existing or newly created variables. NcFilter.write(outfile) writes the new netCDF-file.

New functionality can be added by deriving from NcFilter and utilizing the helper methods. The comand line interface for new functionality can be implemented by adding a function to the class Commands.

Two commands are implemented exemplary:

1. The simple delvar command deletes a variable.
2. The more complex compress packs all suitable variables in a file and saves with zip compression.

The implementation of the compress command is based on a script by Dominik Brunner, Empa.

Usage:

usage: ncfilter.py [-h] COMMAND [ARG [ARG ...]] INFILE OUTFILE

Performs operations on a netCDF file.

positional arguments:
  COMMAND     possible commands: ['compress', 'delvar']
  ARG         arguments for commands
                  "compress": ARG = compression_level (int), default=9
                  "delvar": ARG = variable_to_delete (str)
  INFILE      input file
  OUTFILE     output file

optional arguments:
  -h, --help  show this help message and exit

OUTFILE = INFILE will replace the INFILE with the OUTFILE.