CFA Creator

The cfapyx engine also contains a class for use when creating CFA-netCDF files. These automatically follow the Aggregation conventions for CF-1.12.

Logging

To enable the logger for cfapyx, import the logging package and set the basic config for logging operations. Log level and log message format should be specified here.

import logging
logging.basicConfig(level=logging.DEBUG, format='%(levelname)s [%(name)s]: %(message)s')

Create

To then use the creator functionality from this package, use the following.

from cfapyx import CFANetCDF

ds = CFANetCDF(
    set_of_files, # The set of files to be aggregated
    concat_msg = 'See individual files for more details', # Replaces attributes that differ
)

The aggregated dataset can then be created using the create method. Additional kwargs are:

updates: Update the values of global attributes with new values.
removals: Remove/Ignore some attributes in the Aggregated file.
agg_dims: If the aggregation dimensions are known, state them here. This will improve performance if there are many dimensions that are not aggregated.

ds.create(
    updates = {'tracking_id':'1'},
    removals = ["PI's dog's name"],
    agg_dims = ['time']
)

It is advised that you check how variables and dimensions have been arranged by cfapyx, which are evident from the properties below:

ds.agg_dims
#  - The dimensions that are aggregated across the set of files
ds.coord_dims
#  - Dimensions which also link to a variable (e.g lat/lon)
ds.pure_dims
#  - Dimensions which have a size but no variable/array component.

ds.aggregated_vars
#  - Variables which change across the aggregation dimension(s)
ds.identical_vars
#  - Variables which do not change across the aggregation dimension(s)
ds.scalar_vars
#  - Single-valued variables with no dimensions.

Write

Finally the created dataset can be written to a CFA-netCDF file using the following.

ds.write(output_file)

This file may be read into Xarray as a familiar xarray dataset with:

xarray_ds = xarray.open_dataset(output_file, engine='CFA')

Where the engine is required to decode the aggregation instructions contained in the CFA-netCDF file. Note that without this engine the aggregation instructions will be displayed but not decoded.