# tensorplay.functional.where

Source: https://www.tensorplay.cn/docs/generated/tensorplay.functional.where.html

```python
tensorplay.functional.where(condition, input, other, *, out=None) → Tensor
```

Return a tensor of elements selected from either input or other, depending on condition.

The operation is defined as:

$$\begin{split}\text{out}_i = \begin{cases}
    \text{input}_i & \text{if } \text{condition}_i \\
    \text{other}_i & \text{otherwise} \\
\end{cases}\end{split}$$

> **Note**
>
> The tensors condition, input, other must be broadcastable.

Parameters:

- condition (BoolTensor) – When True (nonzero), yield input, otherwise yield other

- input ([Tensor](/docs/generated/tensorplay.Tensor.html#tensorplay.Tensor) or [Scalar](/docs/generated/tensorplay.Scalar.html#tensorplay.Scalar)) – value (if input is a scalar) or values selected at indices where condition is True

- other ([Tensor](/docs/generated/tensorplay.Tensor.html#tensorplay.Tensor) or [Scalar](/docs/generated/tensorplay.Scalar.html#tensorplay.Scalar)) – value (if other is a scalar) or values selected at indices where condition is False

Keyword Arguments:

out ([Tensor](/docs/generated/tensorplay.Tensor.html#tensorplay.Tensor), optional) – the output tensor.

Returns:

A tensor of shape equal to the broadcasted shape of condition, input, other

Return type:

[Tensor](/docs/generated/tensorplay.Tensor.html#tensorplay.Tensor)

Example:

```
>>> x = tensorplay.randn(3, 2)
>>> y = tensorplay.ones(3, 2)
>>> x
tensor([[-0.4620,  0.3139],
        [ 0.3898, -0.7197],
        [ 0.0478, -0.1657]])
>>> tensorplay.where(x > 0, 1.0, 0.0)
tensor([[0., 1.],
        [1., 0.],
        [1., 0.]])
>>> tensorplay.where(x > 0, x, y)
tensor([[ 1.0000,  0.3139],
        [ 0.3898,  1.0000],
        [ 0.0478,  1.0000]])
>>> x = tensorplay.randn(2, 2, dtype=tensorplay.double)
>>> x
tensor([[ 1.0779,  0.0383],
        [-0.8785, -1.1089]], dtype=tensorplay.float64)
>>> tensorplay.where(x > 0, x, 0.)
tensor([[1.0779, 0.0383],
        [0.0000, 0.0000]], dtype=tensorplay.float64)
```

```python
tensorplay.functional.where(condition) → tuple of LongTensor
```

tensorplay.where(condition) is identical to
tensorplay.nonzero(condition, as_tuple=True).

> **Note**
>
> See also tensorplay.nonzero().