ak.contents.UnionArray
----------------------

.. py:module: ak.contents.UnionArray

Defined in `awkward.contents.unionarray <https://github.com/scikit-hep/awkward/blob/e9dd2694cf5c6ccb1717358fe926816d8ecbfb9c/src/awkward/contents/unionarray.py>`__ on `line 53 <https://github.com/scikit-hep/awkward/blob/e9dd2694cf5c6ccb1717358fe926816d8ecbfb9c/src/awkward/contents/unionarray.py#L53>`__.

.. py:class:: ak.contents.UnionArray(self, tags, index, contents, *, parameters=None)

UnionArray represents data drawn from an ordered list of ``contents``,
which can have different types, using

* ``tags``: buffer of integers indicating which content each array element draws from.
* ``index``: buffer of integers indicating which element from the content to draw from.

UnionArrays correspond to Apache Arrow's
`dense union type <https://arrow.apache.org/docs/format/Columnar.html#dense-union>`__.
Awkward Array has no direct equivalent for Apache Arrow's
`sparse union type <https://arrow.apache.org/docs/format/Columnar.html#sparse-union>`__.

To illustrate how the constructor arguments are interpreted, the following is a
simplified implementation of ``__init__``, ``__len__``, and ``__getitem__``:

.. code-block:: python


    class UnionArray(Content):
        def __init__(self, tags, index, contents):
            assert isinstance(tags, Index8)
            assert isinstance(index, (Index32, IndexU32, Index64))
            assert isinstance(contents, list)
            assert len(index) >= len(tags)  # usually equal
            for x in tags:
                assert 0 <= x < len(contents)
            for i, x in enumerate(tags):
                assert 0 <= index[i] < len(contents[x])
            self.tags = tags
            self.index = index
            self.contents = contents

        def __len__(self):
            return len(self.tags)

        def __getitem__(self, where):
            if isinstance(where, int):
                if where < 0:
                    where += len(self)
                assert 0 <= where < len(self)
                return self.contents[self.tags[where]][self.index[where]]

            elif isinstance(where, slice) and where.step is None:
                return UnionArray(
                    self.tags[where], self.index[where], self.contents
                )

            elif isinstance(where, str):
                return UnionArray(
                    self.tags, self.index, [x[where] for x in self.contents]
                )

            else:
                raise AssertionError(where)



.. _ak-contents-unionarray-tags:

.. py:attribute:: ak.contents.UnionArray.tags



.. _ak-contents-unionarray-index:

.. py:attribute:: ak.contents.UnionArray.index



.. _ak-contents-unionarray-copy:

.. py:method:: ak.contents.UnionArray.copy(self, tags=UNSET, index=UNSET, contents=UNSET, *, parameters=UNSET)



.. _ak-contents-unionarray-__copy__:

.. py:method:: ak.contents.UnionArray.__copy__(self)



.. _ak-contents-unionarray-__deepcopy__:

.. py:method:: ak.contents.UnionArray.__deepcopy__(self, memo)



.. _ak-contents-unionarray-simplified:

.. py:method:: ak.contents.UnionArray.simplified(cls, tags, index, contents, *, parameters=None, mergebool=False)



.. _ak-contents-unionarray-_form_with_key:

.. py:method:: ak.contents.UnionArray._form_with_key(self, getkey)



.. _ak-contents-unionarray-_to_buffers:

.. py:method:: ak.contents.UnionArray._to_buffers(self, form, getkey, container, backend, byteorder)



.. _ak-contents-unionarray-_to_typetracer:

.. py:method:: ak.contents.UnionArray._to_typetracer(self, forget_length)



.. _ak-contents-unionarray-_touch_data:

.. py:method:: ak.contents.UnionArray._touch_data(self, recursive)



.. _ak-contents-unionarray-_touch_shape:

.. py:method:: ak.contents.UnionArray._touch_shape(self, recursive)



.. _ak-contents-unionarray-length:

.. py:attribute:: ak.contents.UnionArray.length



.. _ak-contents-unionarray-__repr__:

.. py:method:: ak.contents.UnionArray.__repr__(self)



.. _ak-contents-unionarray-_repr:

.. py:method:: ak.contents.UnionArray._repr(self, indent, pre, post)



.. _ak-contents-unionarray-_getitem_nothing:

.. py:method:: ak.contents.UnionArray._getitem_nothing(self)



.. _ak-contents-unionarray-_is_getitem_at_placeholder:

.. py:method:: ak.contents.UnionArray._is_getitem_at_placeholder(self)



.. _ak-contents-unionarray-_getitem_at:

.. py:method:: ak.contents.UnionArray._getitem_at(self, where)



.. _ak-contents-unionarray-_getitem_range:

.. py:method:: ak.contents.UnionArray._getitem_range(self, start, stop)



.. _ak-contents-unionarray-_getitem_field:

.. py:method:: ak.contents.UnionArray._getitem_field(self, where, only_fields=())



.. _ak-contents-unionarray-_getitem_fields:

.. py:method:: ak.contents.UnionArray._getitem_fields(self, where, only_fields=())



.. _ak-contents-unionarray-_carry:

.. py:method:: ak.contents.UnionArray._carry(self, carry, allow_lazy)



.. _ak-contents-unionarray-_union_of_optionarrays:

.. py:method:: ak.contents.UnionArray._union_of_optionarrays(self, index, parameters)



.. _ak-contents-unionarray-project:

.. py:method:: ak.contents.UnionArray.project(self, index)



.. _ak-contents-unionarray-regular_index:

.. py:method:: ak.contents.UnionArray.regular_index(tags, *, backend, index_cls=Index64)



.. _ak-contents-unionarray-_regular_index:

.. py:method:: ak.contents.UnionArray._regular_index(self, tags)



.. _ak-contents-unionarray-nested_tags_index:

.. py:method:: ak.contents.UnionArray.nested_tags_index(offsets, counts, *, backend, tags_cls=Index8, index_cls=Index64)



.. _ak-contents-unionarray-_getitem_next_jagged_generic:

.. py:method:: ak.contents.UnionArray._getitem_next_jagged_generic(self, slicestarts, slicestops, slicecontent, tail)



.. _ak-contents-unionarray-_getitem_next_jagged:

.. py:method:: ak.contents.UnionArray._getitem_next_jagged(self, slicestarts, slicestops, slicecontent, tail)



.. _ak-contents-unionarray-_getitem_next:

.. py:method:: ak.contents.UnionArray._getitem_next(self, head, tail, advanced)



.. _ak-contents-unionarray-_offsets_and_flattened:

.. py:method:: ak.contents.UnionArray._offsets_and_flattened(self, axis, depth)



.. _ak-contents-unionarray-_mergeable_next:

.. py:method:: ak.contents.UnionArray._mergeable_next(self, other, mergebool)



.. _ak-contents-unionarray-_merging_strategy:

.. py:method:: ak.contents.UnionArray._merging_strategy(self, others)



.. _ak-contents-unionarray-_reverse_merge:

.. py:method:: ak.contents.UnionArray._reverse_merge(self, other)



.. _ak-contents-unionarray-_mergemany:

.. py:method:: ak.contents.UnionArray._mergemany(self, others)



.. _ak-contents-unionarray-_fill_none:

.. py:method:: ak.contents.UnionArray._fill_none(self, value)



.. _ak-contents-unionarray-_local_index:

.. py:method:: ak.contents.UnionArray._local_index(self, axis, depth)



.. _ak-contents-unionarray-_combinations:

.. py:method:: ak.contents.UnionArray._combinations(self, n, replacement, recordlookup, parameters, axis, depth)



.. _ak-contents-unionarray-_numbers_to_type:

.. py:method:: ak.contents.UnionArray._numbers_to_type(self, name, including_unknown)



.. _ak-contents-unionarray-_is_unique:

.. py:method:: ak.contents.UnionArray._is_unique(self, negaxis, starts, parents, outlength)



.. _ak-contents-unionarray-_unique:

.. py:method:: ak.contents.UnionArray._unique(self, negaxis, starts, parents, outlength)



.. _ak-contents-unionarray-_argsort_next:

.. py:method:: ak.contents.UnionArray._argsort_next(self, negaxis, starts, shifts, parents, outlength, ascending, stable)



.. _ak-contents-unionarray-_sort_next:

.. py:method:: ak.contents.UnionArray._sort_next(self, negaxis, starts, parents, outlength, ascending, stable)



.. _ak-contents-unionarray-_reduce_next:

.. py:method:: ak.contents.UnionArray._reduce_next(self, reducer, negaxis, starts, shifts, parents, outlength, mask, keepdims, behavior)



.. _ak-contents-unionarray-_validity_error:

.. py:method:: ak.contents.UnionArray._validity_error(self, path)



.. _ak-contents-unionarray-_nbytes_part:

.. py:method:: ak.contents.UnionArray._nbytes_part(self)



.. _ak-contents-unionarray-_pad_none:

.. py:method:: ak.contents.UnionArray._pad_none(self, target, axis, depth, clip)



.. _ak-contents-unionarray-_to_arrow:

.. py:method:: ak.contents.UnionArray._to_arrow(self, pyarrow, mask_node, validbytes, length, options)



.. _ak-contents-unionarray-_to_backend_array:

.. py:method:: ak.contents.UnionArray._to_backend_array(self, allow_missing, backend)



.. _ak-contents-unionarray-_remove_structure:

.. py:method:: ak.contents.UnionArray._remove_structure(self, backend, options)



.. _ak-contents-unionarray-_recursively_apply:

.. py:method:: ak.contents.UnionArray._recursively_apply(self, action, depth, depth_context, lateral_context, options)



.. _ak-contents-unionarray-to_packed:

.. py:method:: ak.contents.UnionArray.to_packed(self, recursive=True)



.. _ak-contents-unionarray-_to_list:

.. py:method:: ak.contents.UnionArray._to_list(self, behavior, json_conversions)



.. _ak-contents-unionarray-_to_backend:

.. py:method:: ak.contents.UnionArray._to_backend(self, backend)



.. _ak-contents-unionarray-_is_equal_to:

.. py:method:: ak.contents.UnionArray._is_equal_to(self, other, index_dtype, numpyarray, all_parameters)