Incompatible differences between versions 2.x and 3.x

For those familiar with the cf-python API at version 2.x, some important, backwards incompatible changes were introduced at version 3.0.0.

Scripts written for version 2.x but running under version 3.x should either work as expected, or provide informative error messages on the new API usage. However, it is advised that the outputs of older scripts are checked when running with Python 3 versions of the cf library.

Python

Version 3.x only works for Python 3.5 or later. Version 2.x only works for python version 2.7.

In-place operations

At version 3.x, in-place operations return None, rather than the modified construct. The keyword that defines the operation to be in-place is now inplace (rather than i).

>>> g = f.tranpose()
>>> print(type(g))
<class 'cf.field.Field'>
>>> x = f.tranpose(inplace=True)
>>> print(x)
None

Field creation

Field construct creation is has changed in two notable ways:

Firstly, a single method cf.Field.set_construct has replaced the separated methods for each construct type (e.g. cf.Field.insert_dim).

Secondly, domain axis constructs are no longer created on-demand when data or dimension coordinate constructs are set on the new field construct. i.e the domain axis constructs have to be created explicitly before any data or metadata constructs that use them are set on the field construct:

>>> f = cf.Field()
>>> f.set_construct(cf.DomainAxis(73))
>>> f.set_construct(cf.DomainAxis(96))
>>> data = cf.Data(numpy.arange(7008.).reshape(73, 96))
>>> f.set_data(data)

Note that the cf.Field.set_data and cf.Field.set_construct methods are able to match up existing domain axis constructs to the new data or construct if the mapping can be made unambiguously (as is the case in the above example).

New methods that replace deprecated ones

Version 3.x methods that replace deprecated version 2.x methods:

Version 3.x	Version 2.x
cf.Field.cell_methods.ordered	cf.Field.CellMethods
cf.Field.convert	cf.Field.field
cf.Field.domain_axis_identity	cf.Field.axis_name
cf.Field.del_construct	cf.Field.remove_item
cf.Field.get_data_axes	cf.Field.data_axes, cf.Field.item_axes
cf.Field.insert_dimension	cf.Field.expand_dims
cf.Field.nc_del_variable	cf.Field.ncvar
cf.Field.nc_get_variable	cf.Field.ncvar
cf.Field.nc_set_variable	cf.Field.ncvar
cf.Field.set_construct	cf.Field.insert_aux, cf.Field.insert_axis, cf.Field.insert_dim, cf.Field.insert_domain_anc, cf.Field.insert_field_anc, cf.Field.insert_item, cf.Field.insert_measure, cf.Field.insert_ref
cf.Field.set_data	cf.Field.insert_data
cf.Constructs.data_axes	cf.Field.items_axes
cf.Data.nc_hdf5_chunksizes	cf.Field.HDF_chunks
cf.Data.nc_set_hdf5_chunksizes	cf.Field.HDF_chunks
cf.Data.nc_clear_hdf5_chunksizes	cf.Field.HDF_chunks

Changes to the API of existing methods

Methods that have a different API in version 3.x

Version 3.x	API changes compared to version 2.x
cf.Field.anchor	inplace replaces i parameter. No **kwargs parameters.
cf.Field.aux	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.auxs	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.axes	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.axes_names	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.axis	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.axis_size	identity replaces axes parameter. No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.ceil	inplace replaces i parameter. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.cell_area	No insert parameter.
cf.Field.clip	inplace replaces i parameter.
cf.Field.collapse	New verbose parameter. inplace replaces i parameter. No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.convert_reference_time	inplace replaces i parameter.
cf.Field.convolution_filter	inplace replaces i parameter. weights parameter can not be a string. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.coord	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.coords	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.cos	inplace replaces i parameter.
cf.Field.cyclic	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.derivative	inplace replaces i parameter. wrap replaces cyclic parameter. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.dim	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.dims	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.direction	No axes parameter. No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.domain_anc	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.domain_ancs	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.exp	inplace replaces i parameter.
cf.Field.field_anc	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.field_ancs	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.flip	inplace replaces i parameter. No **kwargs parameters.
cf.Field.floor	inplace replaces i parameter.
cf.Field.identity	No relaxed_identity parameter.
cf.Field.indices	No 'exact' mode. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.iscyclic	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.item	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.items	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.key	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.log	inplace replaces i parameter.
cf.Field.mask_invalid	inplace replaces i parameter.
cf.Field.measure	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.measures	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.override_calendar	inplace replaces i parameter.
cf.Field.override_units	inplace replaces i parameter.
cf.Field.period	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.ref	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.refs	No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.regridc	inplace replaces i parameter. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.regrids	inplace replaces i parameter. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.rint	inplace replaces i parameter.
cf.Field.roll	inplace replaces i parameter. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.round	inplace replaces i parameter.
cf.Field.sin	inplace replaces i parameter.
cf.Field.squeeze	inplace replaces i parameter. Construct identity arguments are no longer assumed to be an abbreviation. No **kwargs parameters.
cf.Field.tan	inplace replaces i parameter.
cf.Field.tranpose	inplace replaces i parameter. constructs replaces items parameter. No **kwargs parameters. Construct identity arguments are no longer assumed to be an abbreviation.
cf.Field.trunc	inplace replaces i parameter.
cf.Field.unsqueeze	inplace replaces i parameter. No axes parameter. No **kwargs parameters.
cf.Field.where	inplace replaces i parameter. construct replaces item parameter. No axes parameter. No **item_options parameters. Construct identity arguments are no longer assumed to be an abbreviation.