ak.contents.IndexedArray
------------------------

.. py:module: ak.contents.IndexedArray

Defined in `awkward.contents.indexedarray <https://github.com/scikit-hep/awkward/blob/28c96fed31d74bd32335f1cb9a1c71a1a7232bc7/src/awkward/contents/indexedarray.py>`__ on `line 55 <https://github.com/scikit-hep/awkward/blob/28c96fed31d74bd32335f1cb9a1c71a1a7232bc7/src/awkward/contents/indexedarray.py#L55>`__.

.. py:class:: ak.contents.IndexedArray(self, index, content, *, parameters=None)

IndexedArray is a general-purpose tool for *lazily* changing the order of
and/or duplicating some ``content`` with a
`np.take <https://docs.scipy.org/doc/numpy/reference/generated/numpy.take.html>`__
over the integer buffer ``index.

It has many uses:

* representing a lazily applied slice.
* simulating pointers into another collection.
* emulating the dictionary encoding of Apache Arrow and Parquet.

If the ``__array__`` parameter is ``"categorical"``, the contents must be unique.
Some operations are optimized (for instance, ``==`` only compares ``index`` integers)
and the array can be converted to and from Arrow/Parquet's dictionary encoding.

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

.. code-block:: python


    class IndexedArray(Content):
        def __init__(self, index, content):
            assert isinstance(index, (Index32, IndexU32, Index64))
            assert isinstance(content, Content)
            for x in index:
                assert 0 <= x < len(content)  # index[i] must not be negative
            self.index = index
            self.content = content

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

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

            elif isinstance(where, slice) and where.step is None:
                return IndexedArray(
                    self.index[where.start : where.stop], self.content
                )

            elif isinstance(where, str):
                return IndexedArray(self.index, self.content[where])

            else:
                raise AssertionError(where)



.. _ak-contents-indexedarray-index:

.. py:attribute:: ak.contents.IndexedArray.index



.. _ak-contents-indexedarray-copy:

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



.. _ak-contents-indexedarray-__copy__:

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



.. _ak-contents-indexedarray-__deepcopy__:

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



.. _ak-contents-indexedarray-simplified:

.. py:method:: ak.contents.IndexedArray.simplified(cls, index, content, *, parameters=None)



.. _ak-contents-indexedarray-_form_with_key:

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



.. _ak-contents-indexedarray-_form_with_key_path:

.. py:method:: ak.contents.IndexedArray._form_with_key_path(self, path)



.. _ak-contents-indexedarray-_to_buffers:

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



.. _ak-contents-indexedarray-_to_typetracer:

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



.. _ak-contents-indexedarray-_touch_data:

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



.. _ak-contents-indexedarray-_touch_shape:

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



.. _ak-contents-indexedarray-length:

.. py:attribute:: ak.contents.IndexedArray.length



.. _ak-contents-indexedarray-__repr__:

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



.. _ak-contents-indexedarray-_repr:

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



.. _ak-contents-indexedarray-to_indexedoptionarray64:

.. py:method:: ak.contents.IndexedArray.to_IndexedOptionArray64(self)



.. _ak-contents-indexedarray-mask_as_bool:

.. py:method:: ak.contents.IndexedArray.mask_as_bool(self, valid_when=True)



.. _ak-contents-indexedarray-_getitem_nothing:

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



.. _ak-contents-indexedarray-_is_getitem_at_placeholder:

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



.. _ak-contents-indexedarray-_getitem_at:

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



.. _ak-contents-indexedarray-_getitem_range:

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



.. _ak-contents-indexedarray-_getitem_field:

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



.. _ak-contents-indexedarray-_getitem_fields:

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



.. _ak-contents-indexedarray-_carry:

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



.. _ak-contents-indexedarray-_getitem_next_jagged_generic:

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



.. _ak-contents-indexedarray-_getitem_next_jagged:

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



.. _ak-contents-indexedarray-_getitem_next:

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



.. _ak-contents-indexedarray-project:

.. py:method:: ak.contents.IndexedArray.project(self, mask=None)



.. _ak-contents-indexedarray-_offsets_and_flattened:

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



.. _ak-contents-indexedarray-_mergeable_next:

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



.. _ak-contents-indexedarray-_merging_strategy:

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



.. _ak-contents-indexedarray-_reverse_merge:

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



.. _ak-contents-indexedarray-_mergemany:

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



.. _ak-contents-indexedarray-_fill_none:

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



.. _ak-contents-indexedarray-_local_index:

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



.. _ak-contents-indexedarray-_unique_index:

.. py:method:: ak.contents.IndexedArray._unique_index(self, index, sorted=True)



.. _ak-contents-indexedarray-_numbers_to_type:

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



.. _ak-contents-indexedarray-_is_unique:

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



.. _ak-contents-indexedarray-_unique:

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



.. _ak-contents-indexedarray-_argsort_next:

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



.. _ak-contents-indexedarray-_sort_next:

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



.. _ak-contents-indexedarray-_combinations:

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



.. _ak-contents-indexedarray-_reduce_next:

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



.. _ak-contents-indexedarray-_validity_error:

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



.. _ak-contents-indexedarray-_nbytes_part:

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



.. _ak-contents-indexedarray-_pad_none:

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



.. _ak-contents-indexedarray-_to_arrow:

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



.. _ak-contents-indexedarray-_to_cudf:

.. py:method:: ak.contents.IndexedArray._to_cudf(self, cudf, mask, length)



.. _ak-contents-indexedarray-_to_backend_array:

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



.. _ak-contents-indexedarray-_remove_structure:

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



.. _ak-contents-indexedarray-_recursively_apply:

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



.. _ak-contents-indexedarray-to_packed:

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



.. _ak-contents-indexedarray-_to_list:

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



.. _ak-contents-indexedarray-_to_backend:

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



.. _ak-contents-indexedarray-_push_inside_record_or_project:

.. py:method:: ak.contents.IndexedArray._push_inside_record_or_project(self)



.. _ak-contents-indexedarray-_is_equal_to:

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



.. _ak-contents-indexedarray-_trim:

.. py:method:: ak.contents.IndexedArray._trim(self)