Python API

recursive_diff.recursive_diff(lhs, rhs, *, rel_tol=1e-09, abs_tol=0.0, brief_dims=())

Compare two objects and yield all differences. The two objects must any of:

• basic types (str, int, float, bool)
• basic collections (list, tuple, dict, set, frozenset)
• numpy scalar types, e.g. numpy.float64
• numpy.ndarray
• pandas.Series
• pandas.DataFrame
• pandas.Index
• xarray.DataArray
• xarray.Dataset
• any recursive combination of the above
• any other object (compared with ==)

Special treatment is reserved to different types:

• floats and ints are compared with tolerance, using math.isclose()
• NaN equals to NaN
• bools are only equal to other bools
• numpy arrays are compared elementwise and with tolerance, also testing the dtype
• pandas and xarray objects are compared elementwise, with tolerance, and without order. Duplicate indices are not supported.
• xarray dimensions and variables are compared without order
• collections (list, tuple, dict, set, frozenset) are recursively descended into
• generic/unknown objects are compared with ==

Custom classes can be registered to benefit from the above behaviour; see cast().

Parameters:

• lhs – left-hand-side data structure
• rhs – right-hand-side data structure
• rel_tol (float) – relative tolerance when comparing numbers. Applies to floats, integers, and all numpy-based data.
• abs_tol (float) – absolute tolerance when comparing numbers. Applies to floats, integers, and all numpy-based data.
• brief_dims –

  One of:

  • sequence of strings representing xarray dimensions. If one or more differences are found along one of these dimensions, only one message will be reported, stating the differences count.
  • ”all”, to produce one line only for every xarray variable that differs

  Omit to output a line for every single different cell.

Yields strings containing difference messages, prepended by the path to the point that differs.

recursive_diff.recursive_eq(lhs, rhs, rel_tol=1e-09, abs_tol=0.0)

Wrapper around recursive_diff(). Print out all differences and finally assert that there are none.

recursive_diff.cast(obj, brief_dims)

Helper function of recursive_diff().

Cast objects into simpler object types:

• Cast tuple to list
• Cast frozenset to set
• Cast all numpy-based objects to xarray.DataArray, as it is the most generic format that can describe all use cases:
  • numpy.ndarray
  • pandas.Series
  • pandas.DataFrame
  • pandas.Index, except pandas.RangeIndex, which is instead returned unaltered
  • xarray.Dataset

The data will be potentially wrapped by a dict to hold the various attributes and marked so that it doesn’t trigger an infinite recursion.

• Do nothing for any other object types.

Parameters:

• obj – complex object that must be simplified
• brief_dims (tuple) – sequence of xarray dimensions that must be compacted. See documentation on recursive_diff().

Returns:

simpler object to compare