tf.one_hot

tf.one_hot(
    indices,
    depth,
    on_value=None,
    off_value=None,
    axis=None,
    dtype=None,
    name=None
)

Defined in tensorflow/python/ops/array_ops.py.

See the guide: Tensor Transformations > Slicing and Joining

Returns a one-hot tensor.

The locations represented by indices in indices take value on_value, while all other locations take value off_value.

on_value and off_value must have matching data types. If dtype is also provided, they must be the same data type as specified by dtype.

If on_value is not provided, it will default to the value 1 with type dtype

If off_value is not provided, it will default to the value 0 with type dtype

If the input indices is rank N, the output will have rank N+1. The new axis is created at dimension axis (default: the new axis is appended at the end).

If indices is a scalar the output shape will be a vector of length depth

If indices is a vector of length features, the output shape will be:

  features x depth if axis == -1
  depth x features if axis == 0

If indices is a matrix (batch) with shape [batch, features], the output shape will be:

  batch x features x depth if axis == -1
  batch x depth x features if axis == 1
  depth x batch x features if axis == 0

If dtype is not provided, it will attempt to assume the data type of on_value or off_value, if one or both are passed in. If none of on_value, off_value, or dtype are provided, dtype will default to the value tf.float32.

For example:

indices = [0, 1, 2]
depth = 3
tf.one_hot(indices, depth)  # output: [3 x 3]
# [[1., 0., 0.],
#  [0., 1., 0.],
#  [0., 0., 1.]]

indices = [0, 2, -1, 1]
depth = 3
tf.one_hot(indices, depth,
           on_value=5.0, off_value=0.0,
           axis=-1)  # output: [4 x 3]
# [[5.0, 0.0, 0.0],  # one_hot(0)
#  [0.0, 0.0, 5.0],  # one_hot(2)
#  [0.0, 0.0, 0.0],  # one_hot(-1)
#  [0.0, 5.0, 0.0]]  # one_hot(1)

indices = [[0, 2], [1, -1]]
depth = 3
tf.one_hot(indices, depth,
           on_value=1.0, off_value=0.0,
           axis=-1)  # output: [2 x 2 x 3]
# [[[1.0, 0.0, 0.0],   # one_hot(0)
#   [0.0, 0.0, 1.0]],  # one_hot(2)
#  [[0.0, 1.0, 0.0],   # one_hot(1)
#   [0.0, 0.0, 0.0]]]  # one_hot(-1)

Args:

  • indices: A Tensor of indices.
  • depth: A scalar defining the depth of the one hot dimension.
  • on_value: A scalar defining the value to fill in output when indices[j] = i. (default: 1)
  • off_value: A scalar defining the value to fill in output when indices[j] != i. (default: 0)
  • axis: The axis to fill (default: -1, a new inner-most axis).
  • dtype: The data type of the output tensor.
  • name: A name for the operation (optional).

Returns:

  • output: The one-hot tensor.

Raises:

  • TypeError: If dtype of either on_value or off_value don't match dtype
  • TypeError: If dtype of on_value and off_value don't match one another