# Copyright 2017 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
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# ==============================================================================
"""Python wrappers for reader Datasets."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

from tensorflow.python.compat import compat
from tensorflow.python.data.experimental.ops import readers
from tensorflow.python.data.ops import dataset_ops
from tensorflow.python.data.ops import readers as core_readers
from tensorflow.python.framework import dtypes
from tensorflow.python.framework import ops
from tensorflow.python.framework import tensor_spec
from tensorflow.python.ops import gen_experimental_dataset_ops
from tensorflow.python.util import deprecation


@deprecation.deprecated(None,
                        "Use `tf.data.experimental.make_csv_dataset(...)`.")
def make_csv_dataset(
    file_pattern,
    batch_size,
    column_names=None,
    column_defaults=None,
    label_name=None,
    select_columns=None,
    field_delim=",",
    use_quote_delim=True,
    na_value="",
    header=True,
    num_epochs=None,
    shuffle=True,
    shuffle_buffer_size=10000,
    shuffle_seed=None,
    prefetch_buffer_size=None,
    num_parallel_reads=None,
    sloppy=False,
    num_rows_for_inference=100,
    compression_type=None,
):
  """Reads CSV files into a dataset.

  Reads CSV files into a dataset, where each element is a (features, labels)
  tuple that corresponds to a batch of CSV rows. The features dictionary
  maps feature column names to `Tensor`s containing the corresponding
  feature data, and labels is a `Tensor` containing the batch's label data.

  Args:
    file_pattern: List of files or patterns of file paths containing CSV
      records. See `tf.io.gfile.glob` for pattern rules.
    batch_size: An int representing the number of records to combine
      in a single batch.
    column_names: An optional list of strings that corresponds to the CSV
      columns, in order. One per column of the input record. If this is not
      provided, infers the column names from the first row of the records.
      These names will be the keys of the features dict of each dataset element.
    column_defaults: A optional list of default values for the CSV fields. One
      item per selected column of the input record. Each item in the list is
      either a valid CSV dtype (float32, float64, int32, int64, or string), or a
      `Tensor` with one of the aforementioned types. The tensor can either be
      a scalar default value (if the column is optional), or an empty tensor (if
      the column is required). If a dtype is provided instead of a tensor, the
      column is also treated as required. If this list is not provided, tries
      to infer types based on reading the first num_rows_for_inference rows of
      files specified, and assumes all columns are optional, defaulting to `0`
      for numeric values and `""` for string values. If both this and
      `select_columns` are specified, these must have the same lengths, and
      `column_defaults` is assumed to be sorted in order of increasing column
      index.
    label_name: A optional string corresponding to the label column. If
      provided, the data for this column is returned as a separate `Tensor` from
      the features dictionary, so that the dataset complies with the format
      expected by a `tf.Estimator.train` or `tf.Estimator.evaluate` input
      function.
    select_columns: An optional list of integer indices or string column
      names, that specifies a subset of columns of CSV data to select. If
      column names are provided, these must correspond to names provided in
      `column_names` or inferred from the file header lines. When this argument
      is specified, only a subset of CSV columns will be parsed and returned,
      corresponding to the columns specified. Using this results in faster
      parsing and lower memory usage. If both this and `column_defaults` are
      specified, these must have the same lengths, and `column_defaults` is
      assumed to be sorted in order of increasing column index.
    field_delim: An optional `string`. Defaults to `","`. Char delimiter to
      separate fields in a record.
    use_quote_delim: An optional bool. Defaults to `True`. If false, treats
      double quotation marks as regular characters inside of the string fields.
    na_value: Additional string to recognize as NA/NaN.
    header: A bool that indicates whether the first rows of provided CSV files
      correspond to header lines with column names, and should not be included
      in the data.
    num_epochs: An int specifying the number of times this dataset is repeated.
      If None, cycles through the dataset forever.
    shuffle: A bool that indicates whether the input should be shuffled.
    shuffle_buffer_size: Buffer size to use for shuffling. A large buffer size
      ensures better shuffling, but increases memory usage and startup time.
    shuffle_seed: Randomization seed to use for shuffling.
    prefetch_buffer_size: An int specifying the number of feature
      batches to prefetch for performance improvement. Recommended value is the
      number of batches consumed per training step. Defaults to auto-tune.
    num_parallel_reads: Number of threads used to read CSV records from files.
      If >1, the results will be interleaved. Defaults to `1`.
    sloppy: If `True`, reading performance will be improved at
      the cost of non-deterministic ordering. If `False`, the order of elements
      produced is deterministic prior to shuffling (elements are still
      randomized if `shuffle=True`. Note that if the seed is set, then order
      of elements after shuffling is deterministic). Defaults to `False`.
    num_rows_for_inference: Number of rows of a file to use for type inference
      if record_defaults is not provided. If None, reads all the rows of all
      the files. Defaults to 100.
    compression_type: (Optional.) A `tf.string` scalar evaluating to one of
      `""` (no compression), `"ZLIB"`, or `"GZIP"`. Defaults to no compression.

  Returns:
    A dataset, where each element is a (features, labels) tuple that corresponds
    to a batch of `batch_size` CSV rows. The features dictionary maps feature
    column names to `Tensor`s containing the corresponding column data, and
    labels is a `Tensor` containing the column data for the label column
    specified by `label_name`.

  Raises:
    ValueError: If any of the arguments is malformed.
  """
  return readers.make_csv_dataset(
      file_pattern, batch_size, column_names, column_defaults, label_name,
      select_columns, field_delim, use_quote_delim, na_value, header,
      num_epochs, shuffle, shuffle_buffer_size, shuffle_seed,
      prefetch_buffer_size, num_parallel_reads, sloppy, num_rows_for_inference,
      compression_type)


class CsvDataset(readers.CsvDataset):
  """A Dataset comprising lines from one or more CSV files."""

  @deprecation.deprecated(None, "Use `tf.data.experimental.CsvDataset(...)`.")
  def __init__(self,
               filenames,
               record_defaults,
               compression_type=None,
               buffer_size=None,
               header=False,
               field_delim=",",
               use_quote_delim=True,
               na_value="",
               select_cols=None):
    super(CsvDataset, self).__init__(
        filenames, record_defaults, compression_type, buffer_size, header,
        field_delim, use_quote_delim, na_value, select_cols)


@deprecation.deprecated(
    None, "Use `tf.data.experimental.make_batched_features_dataset(...)`.")
def make_batched_features_dataset(file_pattern,
                                  batch_size,
                                  features,
                                  reader=core_readers.TFRecordDataset,
                                  label_key=None,
                                  reader_args=None,
                                  num_epochs=None,
                                  shuffle=True,
                                  shuffle_buffer_size=10000,
                                  shuffle_seed=None,
                                  prefetch_buffer_size=None,
                                  reader_num_threads=None,
                                  parser_num_threads=None,
                                  sloppy_ordering=False,
                                  drop_final_batch=False):
  """Returns a `Dataset` of feature dictionaries from `Example` protos.

  If label_key argument is provided, returns a `Dataset` of tuple
  comprising of feature dictionaries and label.

  Example:

  ```
  serialized_examples = [
    features {
      feature { key: "age" value { int64_list { value: [ 0 ] } } }
      feature { key: "gender" value { bytes_list { value: [ "f" ] } } }
      feature { key: "kws" value { bytes_list { value: [ "code", "art" ] } } }
    },
    features {
      feature { key: "age" value { int64_list { value: [] } } }
      feature { key: "gender" value { bytes_list { value: [ "f" ] } } }
      feature { key: "kws" value { bytes_list { value: [ "sports" ] } } }
    }
  ]
  ```

  We can use arguments:

  ```
  features: {
    "age": FixedLenFeature([], dtype=tf.int64, default_value=-1),
    "gender": FixedLenFeature([], dtype=tf.string),
    "kws": VarLenFeature(dtype=tf.string),
  }
  ```

  And the expected output is:

  ```python
  {
    "age": [[0], [-1]],
    "gender": [["f"], ["f"]],
    "kws": SparseTensor(
      indices=[[0, 0], [0, 1], [1, 0]],
      values=["code", "art", "sports"]
      dense_shape=[2, 2]),
  }
  ```

  Args:
    file_pattern: List of files or patterns of file paths containing
      `Example` records. See `tf.io.gfile.glob` for pattern rules.
    batch_size: An int representing the number of records to combine
      in a single batch.
    features: A `dict` mapping feature keys to `FixedLenFeature` or
      `VarLenFeature` values. See `tf.io.parse_example`.
    reader: A function or class that can be
      called with a `filenames` tensor and (optional) `reader_args` and returns
      a `Dataset` of `Example` tensors. Defaults to `tf.data.TFRecordDataset`.
    label_key: (Optional) A string corresponding to the key labels are stored in
      `tf.Examples`. If provided, it must be one of the `features` key,
      otherwise results in `ValueError`.
    reader_args: Additional arguments to pass to the reader class.
    num_epochs: Integer specifying the number of times to read through the
      dataset. If None, cycles through the dataset forever. Defaults to `None`.
    shuffle: A boolean, indicates whether the input should be shuffled. Defaults
      to `True`.
    shuffle_buffer_size: Buffer size of the ShuffleDataset. A large capacity
      ensures better shuffling but would increase memory usage and startup time.
    shuffle_seed: Randomization seed to use for shuffling.
    prefetch_buffer_size: Number of feature batches to prefetch in order to
      improve performance. Recommended value is the number of batches consumed
      per training step. Defaults to auto-tune.
    reader_num_threads: Number of threads used to read `Example` records. If >1,
      the results will be interleaved. Defaults to `1`.
    parser_num_threads: Number of threads to use for parsing `Example` tensors
      into a dictionary of `Feature` tensors. Defaults to `2`.
    sloppy_ordering: If `True`, reading performance will be improved at
      the cost of non-deterministic ordering. If `False`, the order of elements
      produced is deterministic prior to shuffling (elements are still
      randomized if `shuffle=True`. Note that if the seed is set, then order
      of elements after shuffling is deterministic). Defaults to `False`.
    drop_final_batch: If `True`, and the batch size does not evenly divide the
      input dataset size, the final smaller batch will be dropped. Defaults to
      `False`.

  Returns:
    A dataset of `dict` elements, (or a tuple of `dict` elements and label).
    Each `dict` maps feature keys to `Tensor` or `SparseTensor` objects.

  Raises:
    ValueError: If `label_key` is not one of the `features` keys.
  """
  return readers.make_batched_features_dataset(
      file_pattern, batch_size, features, reader, label_key, reader_args,
      num_epochs, shuffle, shuffle_buffer_size, shuffle_seed,
      prefetch_buffer_size, reader_num_threads, parser_num_threads,
      sloppy_ordering, drop_final_batch)


@deprecation.deprecated(
    None, "Use `tf.data.experimental.make_batched_features_dataset(...)`")
def read_batch_features(file_pattern,
                        batch_size,
                        features,
                        reader=core_readers.TFRecordDataset,
                        reader_args=None,
                        randomize_input=True,
                        num_epochs=None,
                        capacity=10000):
  """Reads batches of Examples.

  Example:

  ```
  serialized_examples = [
    features {
      feature { key: "age" value { int64_list { value: [ 0 ] } } }
      feature { key: "gender" value { bytes_list { value: [ "f" ] } } }
      feature { key: "kws" value { bytes_list { value: [ "code", "art" ] } } }
    },
    features {
      feature { key: "age" value { int64_list { value: [] } } }
      feature { key: "gender" value { bytes_list { value: [ "f" ] } } }
      feature { key: "kws" value { bytes_list { value: [ "sports" ] } } }
    }
  ]
  ```

  We can use arguments:

  ```
  features: {
    "age": FixedLenFeature([], dtype=tf.int64, default_value=-1),
    "gender": FixedLenFeature([], dtype=tf.string),
    "kws": VarLenFeature(dtype=tf.string),
  }
  ```

  And the expected output is:

  ```python
  {
    "age": [[0], [-1]],
    "gender": [["f"], ["f"]],
    "kws": SparseTensor(
      indices=[[0, 0], [0, 1], [1, 0]],
      values=["code", "art", "sports"]
      dense_shape=[2, 2]),
  }
  ```

  Args:
    file_pattern: List of files or patterns of file paths containing
      `Example` records. See `tf.io.gfile.glob` for pattern rules.
    batch_size: An int representing the number of records to combine
      in a single batch.
    features: A `dict` mapping feature keys to `FixedLenFeature` or
      `VarLenFeature` values. See `tf.io.parse_example`.
    reader: A function or class that can be
      called with a `filenames` tensor and (optional) `reader_args` and returns
      a `Dataset` of `Example` tensors. Defaults to `tf.data.TFRecordDataset`.
    reader_args: Additional arguments to pass to the reader class.
    randomize_input: Whether the input should be randomized.
    num_epochs: Integer specifying the number of times to read through the
      dataset. If None, cycles through the dataset forever.
    capacity: Buffer size of the ShuffleDataset. A large capacity ensures better
      shuffling but would increase memory usage and startup time.
  Returns:
    A dict from keys in features to `Tensor` or `SparseTensor` objects.
  """
  dataset = readers.make_batched_features_dataset(
      file_pattern,
      batch_size,
      features,
      reader=reader,
      reader_args=reader_args,
      shuffle=randomize_input,
      num_epochs=num_epochs,
      shuffle_buffer_size=capacity)
  iterator = dataset_ops.make_one_shot_iterator(dataset)
  outputs = iterator.get_next()
  return outputs


class SqlDataset(readers.SqlDataset):
  """A `Dataset` consisting of the results from a SQL query."""

  @deprecation.deprecated(None, "Use `tf.data.experimental.SqlDataset(...)`.")
  def __init__(self, driver_name, data_source_name, query, output_types):
    super(SqlDataset, self).__init__(
        driver_name, data_source_name, query, output_types)


class LMDBDataset(dataset_ops.DatasetSource):
  """A LMDB Dataset that reads the lmdb file."""

  def __init__(self, filenames):
    """Create a `LMDBDataset`.

    `LMDBDataset` allows a user to read data from a mdb file as
    (key value) pairs sequentially.
    For example:
    ```python
    tf.compat.v1.enable_eager_execution()

    dataset = tf.contrib.lmdb.LMDBDataset("/foo/bar.mdb")

    # Prints the (key, value) pairs inside a lmdb file.
    for key, value in dataset:
      print(key, value)
    ```
    Args:
      filenames: A `tf.string` tensor containing one or more filenames.
    """
    self._filenames = ops.convert_to_tensor(
        filenames, dtype=dtypes.string, name="filenames")
    if compat.forward_compatible(2019, 8, 3):
      variant_tensor = gen_experimental_dataset_ops.lmdb_dataset(
          self._filenames, **self._flat_structure)
    else:
      variant_tensor = gen_experimental_dataset_ops.experimental_lmdb_dataset(
          self._filenames, **self._flat_structure)
    super(LMDBDataset, self).__init__(variant_tensor)

  @property
  def element_spec(self):
    return (tensor_spec.TensorSpec([], dtypes.string),
            tensor_spec.TensorSpec([], dtypes.string))
