离散化层

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Discretization class

tf_keras.layers.Discretization(
    bin_boundaries=None,
    num_bins=None,
    epsilon=0.01,
    output_mode="int",
    sparse=False,
    **kwargs
)

A preprocessing layer which buckets continuous features by ranges.

This layer will place each element of its input data into one of several contiguous ranges and output an integer index indicating which range each element was placed in.

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

Input shape

Any tf.Tensor or tf.RaggedTensor of dimension 2 or higher.

Output shape

Same as input shape.

Arguments

• bin_boundaries: A list of bin boundaries. The leftmost and rightmost bins will always extend to -inf and inf, so bin_boundaries=[0., 1., 2.] generates bins (-inf, 0.), [0., 1.), [1., 2.), and [2., +inf). If this option is set, adapt() should not be called.
• num_bins: The integer number of bins to compute. If this option is set, adapt() should be called to learn the bin boundaries.
• epsilon: Error tolerance, typically a small fraction close to zero (e.g. 0.01). Higher values of epsilon increase the quantile approximation, and hence result in more unequal buckets, but could improve performance and resource consumption.
• output_mode: Specification for the output of the layer. Values can be "int", "one_hot", "multi_hot", or "count" configuring the layer as follows:
  • "int": Return the discretized 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. If the last dimension is size 1, will encode on that dimension. If the last dimension is not size 1, will append a new dimension for the encoded output.
  • "multi_hot": Encodes each sample in the input into a single array the same size as num_bins, containing a 1 for each bin index index present in the sample. Treats the last dimension as the sample dimension, if input shape is (..., sample_length), output shape will be (..., num_tokens).
  • "count": As "multi_hot", but the int array contains a count of the number of times the bin index appeared in the sample. Defaults to "int".
• sparse: Boolean. Only applicable to "one_hot", "multi_hot", and "count" output modes. If True, returns a SparseTensor instead of a dense Tensor. Defaults to False.

Examples

Bucketize float values based on provided buckets.

>>> input = np.array([[-1.5, 1.0, 3.4, .5], [0.0, 3.0, 1.3, 0.0]])
>>> layer = tf.keras.layers.Discretization(bin_boundaries=[0., 1., 2.])
>>> layer(input)
<tf.Tensor: shape=(2, 4), dtype=int64, numpy=
array([[0, 2, 3, 1],
       [1, 3, 2, 1]])>

Bucketize float values based on a number of buckets to compute.

>>> input = np.array([[-1.5, 1.0, 3.4, .5], [0.0, 3.0, 1.3, 0.0]])
>>> layer = tf.keras.layers.Discretization(num_bins=4, epsilon=0.01)
>>> layer.adapt(input)
>>> layer(input)
<tf.Tensor: shape=(2, 4), dtype=int64, numpy=
array([[0, 2, 3, 2],
       [1, 3, 3, 1]])>