► Keras 2 API documentation / Layers API / Preprocessing layers / Categorical features preprocessing layers / HashedCrossing layer

HashedCrossing layer

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HashedCrossing class

tf_keras.layers.HashedCrossing(num_bins, output_mode="int", sparse=False, **kwargs)

A preprocessing layer which crosses features using the "hashing trick".

This layer performs crosses of categorical features using the "hashing trick". Conceptually, the transformation can be thought of as: hash(concatenate(features)) % num_bins.

This layer currently only performs crosses of scalar inputs and batches of scalar inputs. Valid input shapes are (batch_size, 1), (batch_size,) and ().

For an overview and full list of preprocessing layers, see the preprocessing guide.

Arguments

  • num_bins: Number of hash bins.
  • output_mode: Specification for the output of the layer. Values can be "int", or "one_hot" configuring the layer as follows:
    • "int": Return the integer bin indices directly.
    • "one_hot": Encodes each individual element in the input into an array the same size as num_bins, containing a 1 at the input's bin index. Defaults to "int".
  • sparse: Boolean. Only applicable to "one_hot" mode. If True, returns a SparseTensor instead of a dense Tensor. Defaults to False.
  • **kwargs: Keyword arguments to construct a layer.

Examples

Crossing two scalar features.

>>> layer = tf.keras.layers.HashedCrossing(
...     num_bins=5)
>>> feat1 = tf.constant(['A', 'B', 'A', 'B', 'A'])
>>> feat2 = tf.constant([101, 101, 101, 102, 102])
>>> layer((feat1, feat2))
<tf.Tensor: shape=(5,), dtype=int64, numpy=array([1, 4, 1, 1, 3])>

Crossing and one-hotting two scalar features.

>>> layer = tf.keras.layers.HashedCrossing(
...     num_bins=5, output_mode='one_hot')
>>> feat1 = tf.constant(['A', 'B', 'A', 'B', 'A'])
>>> feat2 = tf.constant([101, 101, 101, 102, 102])
>>> layer((feat1, feat2))
<tf.Tensor: shape=(5, 5), dtype=float32, numpy=
  array([[0., 1., 0., 0., 0.],
         [0., 0., 0., 0., 1.],
         [0., 1., 0., 0., 0.],
         [0., 1., 0., 0., 0.],
         [0., 0., 0., 1., 0.]], dtype=float32)>
HashedCrossing layer
HashedCrossing class