.. _op_ai_onnx_Where:

Where
=====

- **Domain**: ``ai.onnx``
- **Since version**: 16

Return elements, either from X or Y, depending on condition.

**Inputs**

- **condition** (*B*): When True (nonzero), yield X, otherwise yield Y
- **X** (*T*): values selected at indices where condition is True
- **Y** (*T*): values selected at indices where condition is False

**Outputs**

- **output** (*T*): Tensor of shape equal to the broadcasted shape of condition, X, and Y.

**Type Constraints**

- **B**: Constrain to boolean tensors.
  Allowed types: tensor(bool).
- **T**: Constrain input and output types to all tensor types (including bfloat).
  Allowed types: tensor(bfloat16), 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).

Examples
--------

**test_cc_where_bool**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(2, 2), dtype=bool
        [[ True, False],
         [ True, False]]
      x: shape=(2, 2), dtype=bool
        [[ True,  True],
         [False, False]]
      y: shape=(2, 2), dtype=bool
        [[False, False],
         [ True,  True]]

    Outputs:
      output: shape=(2, 2), dtype=bool
        [[ True, False],
         [False,  True]]

**test_cc_where_double**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(2, 2), dtype=bool
        [[ True, False],
         [ True, False]]
      x: shape=(2, 2), dtype=float64
        [[1., 2.],
         [3., 4.]]
      y: shape=(2, 2), dtype=float64
        [[5., 6.],
         [7., 8.]]

    Outputs:
      output: shape=(2, 2), dtype=float64
        [[1., 6.],
         [3., 8.]]

**test_cc_where_int16**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(2, 2), dtype=bool
        [[ True, False],
         [ True, False]]
      x: shape=(2, 2), dtype=int16
        [[1, 2],
         [3, 4]]
      y: shape=(2, 2), dtype=int16
        [[-5, -6],
         [-7, -8]]

    Outputs:
      output: shape=(2, 2), dtype=int16
        [[ 1, -6],
         [ 3, -8]]

**test_cc_where_int8**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(2, 2), dtype=bool
        [[ True, False],
         [ True, False]]
      x: shape=(2, 2), dtype=int8
        [[1, 2],
         [3, 4]]
      y: shape=(2, 2), dtype=int8
        [[-5, -6],
         [-7, -8]]

    Outputs:
      output: shape=(2, 2), dtype=int8
        [[ 1, -6],
         [ 3, -8]]

**test_cc_where_nan_inf**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(6,), dtype=bool
        [ True, False,  True, False,  True, False]
      x: shape=(6,), dtype=float32
        [ nan,   1.,  inf,   2., -inf,   3.]
      y: shape=(6,), dtype=float32
        [  0.,  nan,   0.,  inf,   0., -inf]

    Outputs:
      output: shape=(6,), dtype=float32
        [ nan,  nan,  inf,  inf, -inf, -inf]

**test_cc_where_nan_inf_bcast**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(2, 1), dtype=bool
        [[ True],
         [False]]
      x: shape=(2, 3), dtype=float32
        [[inf,  1., inf],
         [ 2., inf,  3.]]
      y: shape=(1, 3), dtype=float32
        [[-inf,  nan,   0.]]

    Outputs:
      output: shape=(2, 3), dtype=float32
        [[ inf,   1.,  inf],
         [-inf,  nan,   0.]]

**test_cc_where_string**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(2, 2), dtype=bool
        [[ True, False],
         [ True, False]]
      x: shape=(2, 2), dtype=object
        [['a', 'b'],
         ['c', 'd']]
      y: shape=(2, 2), dtype=object
        [['e', 'f'],
         ['g', 'h']]

    Outputs:
      output: shape=(2, 2), dtype=object
        [['a', 'f'],
         ['c', 'h']]

**test_cc_where_uint16**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(2, 2), dtype=bool
        [[ True, False],
         [ True, False]]
      x: shape=(2, 2), dtype=uint16
        [[1, 2],
         [3, 4]]
      y: shape=(2, 2), dtype=uint16
        [[5, 6],
         [7, 8]]

    Outputs:
      output: shape=(2, 2), dtype=uint16
        [[1, 6],
         [3, 8]]

**test_cc_where_uint32**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(2, 2), dtype=bool
        [[ True, False],
         [ True, False]]
      x: shape=(2, 2), dtype=uint32
        [[1, 2],
         [3, 4]]
      y: shape=(2, 2), dtype=uint32
        [[5, 6],
         [7, 8]]

    Outputs:
      output: shape=(2, 2), dtype=uint32
        [[1, 6],
         [3, 8]]

**test_cc_where_uint64**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(2, 2), dtype=bool
        [[ True, False],
         [ True, False]]
      x: shape=(2, 2), dtype=uint64
        [[1, 2],
         [3, 4]]
      y: shape=(2, 2), dtype=uint64
        [[5, 6],
         [7, 8]]

    Outputs:
      output: shape=(2, 2), dtype=uint64
        [[1, 6],
         [3, 8]]

**test_cc_where_uint8**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(2, 2), dtype=bool
        [[ True, False],
         [ True, False]]
      x: shape=(2, 2), dtype=uint8
        [[1, 2],
         [3, 4]]
      y: shape=(2, 2), dtype=uint8
        [[5, 6],
         [7, 8]]

    Outputs:
      output: shape=(2, 2), dtype=uint8
        [[1, 6],
         [3, 8]]

**test_where_bcast**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(2, 1), dtype=bool
        [[ True],
         [False]]
      x: shape=(2, 3), dtype=int32
        [[1, 2, 3],
         [4, 5, 6]]
      y: shape=(1, 3), dtype=int32
        [[10, 20, 30]]

    Outputs:
      output: shape=(2, 3), dtype=int32
        [[ 1,  2,  3],
         [10, 20, 30]]

**test_where_example**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(2, 2), dtype=bool
        [[ True, False],
         [ True, False]]
      x: shape=(2, 2), dtype=float32
        [[1., 2.],
         [3., 4.]]
      y: shape=(2, 2), dtype=float32
        [[5., 6.],
         [7., 8.]]

    Outputs:
      output: shape=(2, 2), dtype=float32
        [[1., 6.],
         [3., 8.]]

**test_where_long_example**

.. code-block:: text

    Node:
      Where(condition, x, y) -> (output)

.. code-block:: text

    Inputs:
      condition: shape=(2, 2), dtype=bool
        [[ True, False],
         [ True,  True]]
      x: shape=(2, 2), dtype=int64
        [[1, 2],
         [3, 4]]
      y: shape=(2, 2), dtype=int64
        [[9, 8],
         [7, 6]]

    Outputs:
      output: shape=(2, 2), dtype=int64
        [[1, 8],
         [3, 4]]

Differences with previous version (9)
-------------------------------------

**SchemaDiff**: ``Where`` (domain ``'ai.onnx'``)

* old version: 9
* new version: 16
* breaking: no

**Type constraints:**

* changed 'T': added types: ['tensor(bfloat16)']

Version History
---------------

- :doc:`Version 9 <Where-9>`