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.. _op_ai_onnx_Gather-1:

Gather - version 1
==================

This page documents version **1** of operator **Gather**. See :doc:`Gather` for the latest version (since version 13).

- **Domain**: ``ai.onnx``
- **Since version**: 1

Given ``data`` tensor of rank r >= 1, and ``indices`` tensor of rank q, gather
entries of the axis dimension of ``data`` (by default outer-most one as axis=0) indexed by ``indices``, and concatenates
them in an output tensor of rank q + (r - 1).
Example 1:

.. code-block::

      data = [
          [1.0, 1.2],
          [2.3, 3.4],
          [4.5, 5.7],
      ]
      indices = [
          [0, 1],
          [1, 2],
      ]
      output = [
          [
              [1.0, 1.2],
              [2.3, 3.4],
          ],
          [
              [2.3, 3.4],
              [4.5, 5.7],
          ],
      ]

Example 2:

.. code-block::

      data = [
          [1.0, 1.2, 1.9],
          [2.3, 3.4, 3.9],
          [4.5, 5.7, 5.9],
      ]
      indices = [
          [0, 2],
      ]
      axis = 1,
      output = [
          [[1.0, 1.9]],
          [[2.3, 3.9]],
          [[4.5, 5.9]],
      ]


**Inputs**

- **data** (*T*): Tensor of rank r >= 1.
- **indices** (*Tind*): Tensor of int32/int64 indices, of any rank q. All index values are expected to be within bounds. It is an error if any of the index values are out of bounds.

**Outputs**

- **output** (*T*): Tensor of rank q + (r - 1).

**Attributes**

- **axis** (*int*): Which axis to gather on. Negative value means counting dimensions from the back. Accepted range is [-r, r-1]

**Type Constraints**

- **T**: Constrain input and output types to any tensor type.
  Allowed types: tensor(bool), tensor(complex128), tensor(complex64), tensor(double), tensor(float), tensor(float16), tensor(int16), tensor(int32), tensor(int64), tensor(int8), tensor(string), tensor(uint16), tensor(uint32), tensor(uint64), tensor(uint8).
- **Tind**: Constrain indices to integer types
  Allowed types: tensor(int32), tensor(int64).