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# ==============================================================================
"""Keras string lookup preprocessing layer."""

# pylint: disable=g-classes-have-attributes

from keras.engine import base_preprocessing_layer
from keras.layers.preprocessing import index_lookup
import numpy as np
import tensorflow.compat.v2 as tf
from tensorflow.python.platform import tf_logging as logging
from tensorflow.python.util.tf_export import keras_export


@keras_export(
    "keras.layers.IntegerLookup",
    "keras.layers.experimental.preprocessing.IntegerLookup",
    v1=[])
class IntegerLookup(index_lookup.IndexLookup):
  """Reindex integer inputs to be in a contiguous range, via a dict lookup.

  This layer maps a set of arbitrary integer input tokens into indexed
  integer output via a table-based vocabulary lookup. The layer's output indices
  will be contiguously arranged up to the maximum vocab size, even if the input
  tokens are non-continguous or unbounded. The layer supports multiple options
  for encoding the output via `output_mode`, and has optional support for
  out-of-vocabulary (OOV) tokens and masking.

  The vocabulary for the layer must be either supplied on construction or
  learned via `adapt()`. During `adapt()`, the layer will analyze a data set,
  determine the frequency of individual integer tokens, and create a vocabulary
  from them. If the vocabulary is capped in size, the most frequent tokens will
  be used to create the vocabulary and all others will be treated as OOV.

  There are two possible output modes for the layer.
  When `output_mode` is `"int"`,
  input integers are converted to their index in the vocabulary (an integer).
  When `output_mode` is `"multi_hot"`, `"count"`, or `"tf_idf"`, input integers
  are encoded into an array where each dimension corresponds to an element in
  the vocabulary.

  The vocabulary can optionally contain a mask token as well as an OOV token
  (which can optionally occupy multiple indices in the vocabulary, as set
  by `num_oov_indices`).
  The position of these tokens in the vocabulary is fixed. When `output_mode` is
  `"int"`, the vocabulary will begin with the mask token at index 0, followed by
  OOV indices, followed by the rest of the vocabulary. When `output_mode` is
  `"multi_hot"`, `"count"`, or `"tf_idf"` the vocabulary will begin with OOV
  indices and instances of the mask token will be dropped.

  Args:
    max_tokens: Maximum size of the vocabulary for this layer. This should only
      be specified when adapting the vocabulary or when setting
      `pad_to_max_tokens=True`. If None, there is no cap on the size of the
      vocabulary. Note that this size includes the OOV and mask tokens. Defaults
      to None.
    num_oov_indices: The number of out-of-vocabulary tokens to use. If this
      value is more than 1, OOV inputs are modulated to determine their OOV
      value. If this value is 0, OOV inputs will cause an error when calling the
      layer. Defaults to 1.
    mask_token: An integer token that represents masked inputs. When
      `output_mode` is `"int"`, the token is included in vocabulary and mapped
      to index 0. In other output modes, the token will not appear in the
      vocabulary and instances of the mask token in the input will be dropped.
      If set to None, no mask term will be added. Defaults to None.
    oov_token: Only used when `invert` is True. The token to return for OOV
      indices. Defaults to -1.
    vocabulary: Optional. Either an array of integers or a string path to a text
      file. If passing an array, can pass a tuple, list, 1D numpy array, or 1D
      tensor containing the integer vocbulary terms. If passing a file path, the
      file should contain one line per term in the vocabulary. If this argument
      is set, there is no need to `adapt` the layer.
    invert: Only valid when `output_mode` is `"int"`. If True, this layer will
      map indices to vocabulary items instead of mapping vocabulary items to
      indices. Default to False.
    output_mode: Specification for the output of the layer. Defaults to `"int"`.
      Values can be `"int"`, `"one_hot"`, `"multi_hot"`, `"count"`, or
      `"tf_idf"` configuring the layer as follows:
        - `"int"`: Return the vocabulary indices of the input tokens.
        - `"one_hot"`: Encodes each individual element in the input into an
          array the same size as the vocabulary, containing a 1 at the element
          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 the vocabulary, containing a 1 for each vocabulary
          term 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 token at that index appeared in the sample.
        - `"tf_idf"`: As `"multi_hot"`, but the TF-IDF algorithm is applied to
          find the value in each token slot.
      For `"int"` output, any shape of input and output is supported. For all
      other output modes, currently only output up to rank 2 is supported.
    pad_to_max_tokens: Only applicable when `output_mode` is `"multi_hot"`,
      `"count"`, or `"tf_idf"`. If True, the output will have its feature axis
      padded to `max_tokens` even if the number of unique tokens in the
      vocabulary is less than max_tokens, resulting in a tensor of shape
      [batch_size, max_tokens] regardless of vocabulary size. Defaults to False.
    sparse: Boolean. Only applicable when `output_mode` is `"multi_hot"`,
      `"count"`, or `"tf_idf"`. If True, returns a `SparseTensor` instead of a
      dense `Tensor`. Defaults to False.

  Examples:

  **Creating a lookup layer with a known vocabulary**

  This example creates a lookup layer with a pre-existing vocabulary.

  >>> vocab = [12, 36, 1138, 42]
  >>> data = tf.constant([[12, 1138, 42], [42, 1000, 36]])  # Note OOV tokens
  >>> layer = tf.keras.layers.IntegerLookup(vocabulary=vocab)
  >>> layer(data)
  <tf.Tensor: shape=(2, 3), dtype=int64, numpy=
  array([[1, 3, 4],
         [4, 0, 2]])>

  **Creating a lookup layer with an adapted vocabulary**

  This example creates a lookup layer and generates the vocabulary by analyzing
  the dataset.

  >>> data = tf.constant([[12, 1138, 42], [42, 1000, 36]])
  >>> layer = tf.keras.layers.IntegerLookup()
  >>> layer.adapt(data)
  >>> layer.get_vocabulary()
  [-1, 42, 1138, 1000, 36, 12]

  Note that the OOV token -1 have been added to the vocabulary. The remaining
  tokens are sorted by frequency (42, which has 2 occurrences, is first) then
  by inverse sort order.

  >>> data = tf.constant([[12, 1138, 42], [42, 1000, 36]])
  >>> layer = tf.keras.layers.IntegerLookup()
  >>> layer.adapt(data)
  >>> layer(data)
  <tf.Tensor: shape=(2, 3), dtype=int64, numpy=
  array([[5, 2, 1],
         [1, 3, 4]])>


  **Lookups with multiple OOV indices**

  This example demonstrates how to use a lookup layer with multiple OOV indices.
  When a layer is created with more than one OOV index, any OOV tokens are
  hashed into the number of OOV buckets, distributing OOV tokens in a
  deterministic fashion across the set.

  >>> vocab = [12, 36, 1138, 42]
  >>> data = tf.constant([[12, 1138, 42], [37, 1000, 36]])
  >>> layer = tf.keras.layers.IntegerLookup(vocabulary=vocab, num_oov_indices=2)
  >>> layer(data)
  <tf.Tensor: shape=(2, 3), dtype=int64, numpy=
  array([[2, 4, 5],
         [1, 0, 3]])>

  Note that the output for OOV token 37 is 1, while the output for OOV token
  1000 is 0. The in-vocab terms have their output index increased by 1 from
  earlier examples (12 maps to 2, etc) in order to make space for the extra OOV
  token.

  **One-hot output**

  Configure the layer with `output_mode='one_hot'`. Note that the first
  `num_oov_indices` dimensions in the ont_hot encoding represent OOV values.

  >>> vocab = [12, 36, 1138, 42]
  >>> data = tf.constant([12, 36, 1138, 42, 7]) # Note OOV tokens
  >>> layer = tf.keras.layers.IntegerLookup(
  ...     vocabulary=vocab, output_mode='one_hot')
  >>> layer(data)
  <tf.Tensor: shape=(5, 5), dtype=float32, numpy=
    array([[0., 1., 0., 0., 0.],
           [0., 0., 1., 0., 0.],
           [0., 0., 0., 1., 0.],
           [0., 0., 0., 0., 1.],
           [1., 0., 0., 0., 0.]], dtype=float32)>

  **Multi-hot output**

  Configure the layer with `output_mode='multi_hot'`. Note that the first
  `num_oov_indices` dimensions in the multi_hot encoding represent OOV tokens

  >>> vocab = [12, 36, 1138, 42]
  >>> data = tf.constant([[12, 1138, 42, 42], [42, 7, 36, 7]]) # Note OOV tokens
  >>> layer = tf.keras.layers.IntegerLookup(
  ...     vocabulary=vocab, output_mode='multi_hot')
  >>> layer(data)
  <tf.Tensor: shape=(2, 5), dtype=float32, numpy=
    array([[0., 1., 0., 1., 1.],
           [1., 0., 1., 0., 1.]], dtype=float32)>

  **Token count output**

  Configure the layer with `output_mode='count'`. As with multi_hot output, the
  first `num_oov_indices` dimensions in the output represent OOV tokens.

  >>> vocab = [12, 36, 1138, 42]
  >>> data = tf.constant([[12, 1138, 42, 42], [42, 7, 36, 7]]) # Note OOV tokens
  >>> layer = tf.keras.layers.IntegerLookup(
  ...     vocabulary=vocab, output_mode='count')
  >>> layer(data)
  <tf.Tensor: shape=(2, 5), dtype=float32, numpy=
    array([[0., 1., 0., 1., 2.],
           [2., 0., 1., 0., 1.]], dtype=float32)>

  **TF-IDF output**

  Configure the layer with `output_mode='tf_idf'`. As with multi_hot output, the
  first `num_oov_indices` dimensions in the output represent OOV tokens.

  Each token bin will output `token_count * idf_weight`, where the idf weights
  are the inverse document frequency weights per token. These should be provided
  along with the vocabulary. Note that the `idf_weight` for OOV tokens will
  default to the average of all idf weights passed in.

  >>> vocab = [12, 36, 1138, 42]
  >>> idf_weights = [0.25, 0.75, 0.6, 0.4]
  >>> data = tf.constant([[12, 1138, 42, 42], [42, 7, 36, 7]]) # Note OOV tokens
  >>> layer = tf.keras.layers.IntegerLookup(output_mode='tf_idf')
  >>> layer.set_vocabulary(vocab, idf_weights=idf_weights)
  >>> layer(data)
  <tf.Tensor: shape=(2, 5), dtype=float32, numpy=
    array([[0.  , 0.25, 0.  , 0.6 , 0.8 ],
           [1.0 , 0.  , 0.75, 0.  , 0.4 ]], dtype=float32)>

  To specify the idf weights for oov tokens, you will need to pass the entire
  vocabularly including the leading oov token.

  >>> vocab = [-1, 12, 36, 1138, 42]
  >>> idf_weights = [0.9, 0.25, 0.75, 0.6, 0.4]
  >>> data = tf.constant([[12, 1138, 42, 42], [42, 7, 36, 7]]) # Note OOV tokens
  >>> layer = tf.keras.layers.IntegerLookup(output_mode='tf_idf')
  >>> layer.set_vocabulary(vocab, idf_weights=idf_weights)
  >>> layer(data)
  <tf.Tensor: shape=(2, 5), dtype=float32, numpy=
    array([[0.  , 0.25, 0.  , 0.6 , 0.8 ],
           [1.8 , 0.  , 0.75, 0.  , 0.4 ]], dtype=float32)>

  When adapting the layer in tf_idf mode, each input sample will be considered a
  document, and idf weight per token will be calculated as
  `log(1 + num_documents / (1 + token_document_count))`.

  **Inverse lookup**

  This example demonstrates how to map indices to tokens using this layer. (You
  can also use `adapt()` with `inverse=True`, but for simplicity we'll pass the
  vocab in this example.)

  >>> vocab = [12, 36, 1138, 42]
  >>> data = tf.constant([[1, 3, 4], [4, 0, 2]])
  >>> layer = tf.keras.layers.IntegerLookup(vocabulary=vocab, invert=True)
  >>> layer(data)
  <tf.Tensor: shape=(2, 3), dtype=int64, numpy=
  array([[  12, 1138,   42],
         [  42,   -1,   36]])>

  Note that the first index correspond to the oov token by default.


  **Forward and inverse lookup pairs**

  This example demonstrates how to use the vocabulary of a standard lookup
  layer to create an inverse lookup layer.

  >>> vocab = [12, 36, 1138, 42]
  >>> data = tf.constant([[12, 1138, 42], [42, 1000, 36]])
  >>> layer = tf.keras.layers.IntegerLookup(vocabulary=vocab)
  >>> i_layer = tf.keras.layers.IntegerLookup(
  ...     vocabulary=layer.get_vocabulary(), invert=True)
  >>> int_data = layer(data)
  >>> i_layer(int_data)
  <tf.Tensor: shape=(2, 3), dtype=int64, numpy=
  array([[  12, 1138,   42],
         [  42,   -1,   36]])>

  In this example, the input token 1000 resulted in an output of -1, since
  1000 was not in the vocabulary - it got represented as an OOV, and all OOV
  tokens are returned as -1 in the inverse layer. Also, note that for the
  inverse to work, you must have already set the forward layer vocabulary
  either directly or via `adapt()` before calling `get_vocabulary()`.
  """

  def __init__(self,
               max_tokens=None,
               num_oov_indices=1,
               mask_token=None,
               oov_token=-1,
               vocabulary=None,
               invert=False,
               output_mode="int",
               sparse=False,
               pad_to_max_tokens=False,
               **kwargs):
    allowed_dtypes = [tf.int64]

    # Support deprecated args for this layer.
    if "max_values" in kwargs:
      logging.log_first_n(logging.WARN,
                          "max_values is deprecated, use max_tokens instead.",
                          1)
      max_tokens = kwargs["max_values"]
      del kwargs["max_values"]
    if "mask_value" in kwargs:
      logging.log_first_n(logging.WARN,
                          "mask_value is deprecated, use mask_token instead.",
                          1)
      mask_token = kwargs["mask_value"]
      del kwargs["mask_value"]
    if "oov_value" in kwargs:
      logging.log_first_n(logging.WARN,
                          "oov_value is deprecated, use oov_token instead.", 1)
      oov_token = kwargs["oov_value"]
      del kwargs["oov_value"]

    if "dtype" in kwargs and kwargs["dtype"] not in allowed_dtypes:
      raise ValueError("The value of the dtype argument for IntegerLookup may "
                       "only be one of %s." % (allowed_dtypes,))

    if "dtype" not in kwargs:
      kwargs["dtype"] = tf.int64

    # If max_tokens is set, the token must be greater than 1 - otherwise we
    # are creating a 0-element vocab, which doesn't make sense.
    if max_tokens is not None and max_tokens <= 1:
      raise ValueError(
          f"If `max_tokens` is set for `IntegerLookup`, it must be "
          f"greater than 1. Received: max_tokens={max_tokens}.")

    if num_oov_indices < 0:
      raise ValueError(
          f"The value of `num_oov_indices` argument for `IntegerLookup` "
          f"must >= 0. Received num_oov_indices="
          f"{num_oov_indices}.")

    # Make sure mask and oov are of the dtype we want.
    mask_token = None if mask_token is None else np.int64(mask_token)
    oov_token = None if oov_token is None else np.int64(oov_token)

    super(IntegerLookup, self).__init__(
        max_tokens=max_tokens,
        num_oov_indices=num_oov_indices,
        mask_token=mask_token,
        oov_token=oov_token,
        vocabulary=vocabulary,
        invert=invert,
        output_mode=output_mode,
        sparse=sparse,
        pad_to_max_tokens=pad_to_max_tokens,
        **kwargs)
    base_preprocessing_layer.keras_kpl_gauge.get_cell("IntegerLookup").set(True)
