Class TextLineDataset
Defined in tensorflow/python/data/ops/readers.py
.
A Dataset
comprising lines from one or more text files.
__init__
__init__(
filenames,
compression_type=None,
buffer_size=None
)
Creates a TextLineDataset
.
Args:
filenames
: Atf.string
tensor containing one or more filenames.compression_type
: (Optional.) Atf.string
scalar evaluating to one of""
(no compression),"ZLIB"
, or"GZIP"
.buffer_size
: (Optional.) Atf.int64
scalar denoting the number of bytes to buffer. A value of 0 results in the default buffering values chosen based on the compression type.
Properties
output_classes
Returns the class of each component of an element of this dataset.
The expected values are tf.Tensor
and tf.SparseTensor
.
Returns:
A nested structure of Python type
objects corresponding to each
component of an element of this dataset.
output_shapes
Returns the shape of each component of an element of this dataset.
Returns:
A nested structure of tf.TensorShape
objects corresponding to each
component of an element of this dataset.
output_types
Returns the type of each component of an element of this dataset.
Returns:
A nested structure of tf.DType
objects corresponding to each component
of an element of this dataset.
Methods
tf.data.TextLineDataset.__iter__
__iter__()
Creates an Iterator
for enumerating the elements of this dataset.
The returned iterator implements the Python iterator protocol and therefore can only be used in eager mode.
Returns:
An Iterator
over the elements of this dataset.
Raises:
RuntimeError
: If eager execution is not enabled.
tf.data.TextLineDataset.apply
apply(transformation_func)
Applies a transformation function to this dataset.
apply
enables chaining of custom Dataset
transformations, which are
represented as functions that take one Dataset
argument and return a
transformed Dataset
.
For example:
dataset = (dataset.map(lambda x: x ** 2)
.apply(group_by_window(key_func, reduce_func, window_size))
.map(lambda x: x ** 3))
Args:
transformation_func
: A function that takes oneDataset
argument and returns aDataset
.
Returns:
Dataset
: TheDataset
returned by applyingtransformation_func
to this dataset.
tf.data.TextLineDataset.batch
batch(
batch_size,
drop_remainder=False
)
Combines consecutive elements of this dataset into batches.
The tensors in the resulting element will have an additional outer
dimension, which will be batch_size
(or N % batch_size
for the last
element if batch_size
does not divide the number of input elements N
evenly and drop_remainder
is False
). If your program depends on the
batches having the same outer dimension, you should set the drop_remainder
argument to True
to prevent the smaller batch from being produced.
Args:
batch_size
: Atf.int64
scalartf.Tensor
, representing the number of consecutive elements of this dataset to combine in a single batch.drop_remainder
: (Optional.) Atf.bool
scalartf.Tensor
, representing whether the last batch should be dropped in the case it has fewer thanbatch_size
elements; the default behavior is not to drop the smaller batch.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.cache
cache(filename='')
Caches the elements in this dataset.
Args:
filename
: Atf.string
scalartf.Tensor
, representing the name of a directory on the filesystem to use for caching tensors in this Dataset. If a filename is not provided, the dataset will be cached in memory.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.concatenate
concatenate(dataset)
Creates a Dataset
by concatenating given dataset with this dataset.
# NOTE: The following examples use `{ ... }` to represent the
# contents of a dataset.
a = { 1, 2, 3 }
b = { 4, 5, 6, 7 }
# Input dataset and dataset to be concatenated should have same
# nested structures and output types.
# c = { (8, 9), (10, 11), (12, 13) }
# d = { 14.0, 15.0, 16.0 }
# a.concatenate(c) and a.concatenate(d) would result in error.
a.concatenate(b) == { 1, 2, 3, 4, 5, 6, 7 }
Args:
dataset
:Dataset
to be concatenated.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.filter
filter(predicate)
Filters this dataset according to predicate
.
Args:
predicate
: A function mapping a nested structure of tensors (having shapes and types defined byself.output_shapes
andself.output_types
) to a scalartf.bool
tensor.
Returns:
Dataset
: TheDataset
containing the elements of this dataset for whichpredicate
isTrue
.
tf.data.TextLineDataset.flat_map
flat_map(map_func)
Maps map_func
across this dataset and flattens the result.
Use flat_map
if you want to make sure that the order of your dataset
stays the same. For example, to flatten a dataset of batches into a
dataset of their elements:
# NOTE: The following examples use `{ ... }` to represent the
# contents of a dataset. '[...]' represents a tensor.
a = {[1,2,3,4,5], [6,7,8,9], [10]}
a.flat_map(lambda x: Dataset.from_tensor_slices(x)) ==
{[1,2,3,4,5,6,7,8,9,10]}
tf.data.Dataset.interleave()
is a generalization of flat_map
, since
flat_map
produces the same output as
tf.data.Dataset.interleave(cycle_length=1)
Args:
map_func
: A function mapping a nested structure of tensors (having shapes and types defined byself.output_shapes
andself.output_types
) to aDataset
.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.from_generator
from_generator(
generator,
output_types,
output_shapes=None,
args=None
)
Creates a Dataset
whose elements are generated by generator
.
The generator
argument must be a callable object that returns
an object that support the iter()
protocol (e.g. a generator function).
The elements generated by generator
must be compatible with the given
output_types
and (optional) output_shapes
arguments.
For example:
import itertools
tf.enable_eager_execution()
def gen():
for i in itertools.count(1):
yield (i, [1] * i)
ds = tf.data.Dataset.from_generator(
gen, (tf.int64, tf.int64), (tf.TensorShape([]), tf.TensorShape([None])))
for value in ds.take(2):
print value
# (1, array([1]))
# (2, array([1, 1]))
NOTE: The current implementation of Dataset.from_generator()
uses
tf.py_func
and inherits the same constraints. In particular, it
requires the Dataset
- and Iterator
-related operations to be placed
on a device in the same process as the Python program that called
Dataset.from_generator()
. The body of generator
will not be
serialized in a GraphDef
, and you should not use this method if you
need to serialize your model and restore it in a different environment.
NOTE: If generator
depends on mutable global variables or other external
state, be aware that the runtime may invoke generator
multiple times
(in order to support repeating the Dataset
) and at any time
between the call to Dataset.from_generator()
and the production of the
first element from the generator. Mutating global variables or external
state can cause undefined behavior, and we recommend that you explicitly
cache any external state in generator
before calling
Dataset.from_generator()
.
Args:
generator
: A callable object that returns an object that supports theiter()
protocol. Ifargs
is not specified,generator
must take no arguments; otherwise it must take as many arguments as there are values inargs
.output_types
: A nested structure oftf.DType
objects corresponding to each component of an element yielded bygenerator
.output_shapes
: (Optional.) A nested structure oftf.TensorShape
objects corresponding to each component of an element yielded bygenerator
.args
: (Optional.) A tuple oftf.Tensor
objects that will be evaluated and passed togenerator
as NumPy-array arguments.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.from_sparse_tensor_slices
from_sparse_tensor_slices(sparse_tensor)
Splits each rank-N tf.SparseTensor
in this dataset row-wise. (deprecated)
Args:
sparse_tensor
: Atf.SparseTensor
.
Returns:
Dataset
: ADataset
of rank-(N-1) sparse tensors.
tf.data.TextLineDataset.from_tensor_slices
from_tensor_slices(tensors)
Creates a Dataset
whose elements are slices of the given tensors.
Note that if tensors
contains a NumPy array, and eager execution is not
enabled, the values will be embedded in the graph as one or more
tf.constant
operations. For large datasets (> 1 GB), this can waste
memory and run into byte limits of graph serialization. If tensors
contains one or more large NumPy arrays, consider the alternative described
in this guide.
Args:
tensors
: A nested structure of tensors, each having the same size in the 0th dimension.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.from_tensors
from_tensors(tensors)
Creates a Dataset
with a single element, comprising the given tensors.
Note that if tensors
contains a NumPy array, and eager execution is not
enabled, the values will be embedded in the graph as one or more
tf.constant
operations. For large datasets (> 1 GB), this can waste
memory and run into byte limits of graph serialization. If tensors
contains one or more large NumPy arrays, consider the alternative described
in this
guide.
Args:
tensors
: A nested structure of tensors.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.interleave
interleave(
map_func,
cycle_length,
block_length=1,
num_parallel_calls=None
)
Maps map_func
across this dataset, and interleaves the results.
For example, you can use Dataset.interleave()
to process many input files
concurrently:
# Preprocess 4 files concurrently, and interleave blocks of 16 records from
# each file.
filenames = ["/var/data/file1.txt", "/var/data/file2.txt", ...]
dataset = (Dataset.from_tensor_slices(filenames)
.interleave(lambda x:
TextLineDataset(x).map(parse_fn, num_parallel_calls=1),
cycle_length=4, block_length=16))
The cycle_length
and block_length
arguments control the order in which
elements are produced. cycle_length
controls the number of input elements
that are processed concurrently. If you set cycle_length
to 1, this
transformation will handle one input element at a time, and will produce
identical results to tf.data.Dataset.flat_map
. In general,
this transformation will apply map_func
to cycle_length
input elements,
open iterators on the returned Dataset
objects, and cycle through them
producing block_length
consecutive elements from each iterator, and
consuming the next input element each time it reaches the end of an
iterator.
For example:
# NOTE: The following examples use `{ ... }` to represent the
# contents of a dataset.
a = { 1, 2, 3, 4, 5 }
# NOTE: New lines indicate "block" boundaries.
a.interleave(lambda x: Dataset.from_tensors(x).repeat(6),
cycle_length=2, block_length=4) == {
1, 1, 1, 1,
2, 2, 2, 2,
1, 1,
2, 2,
3, 3, 3, 3,
4, 4, 4, 4,
3, 3,
4, 4,
5, 5, 5, 5,
5, 5,
}
NOTE: The order of elements yielded by this transformation is
deterministic, as long as map_func
is a pure function. If
map_func
contains any stateful operations, the order in which
that state is accessed is undefined.
Args:
map_func
: A function mapping a nested structure of tensors (having shapes and types defined byself.output_shapes
andself.output_types
) to aDataset
.cycle_length
: The number of elements from this dataset that will be processed concurrently.block_length
: The number of consecutive elements to produce from each input element before cycling to another input element.num_parallel_calls
: (Optional.) If specified, the implementation creates a threadpool, which is used to fetch inputs from cycle elements asynchronously and in parallel. The default behavior is to fetch inputs from cycle elements synchronously with no parallelism. If the valuetf.data.experimental.AUTOTUNE
is used, then the number of parallel calls is set dynamically based on available CPU.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.list_files
list_files(
file_pattern,
shuffle=None,
seed=None
)
A dataset of all files matching one or more glob patterns.
NOTE: The default behavior of this method is to return filenames in
a non-deterministic random shuffled order. Pass a seed
or shuffle=False
to get results in a deterministic order.
Example: If we had the following files on our filesystem: - /path/to/dir/a.txt - /path/to/dir/b.py - /path/to/dir/c.py If we pass "/path/to/dir/*.py" as the directory, the dataset would produce: - /path/to/dir/b.py - /path/to/dir/c.py
Args:
file_pattern
: A string, a list of strings, or atf.Tensor
of string type (scalar or vector), representing the filename glob (i.e. shell wildcard) pattern(s) that will be matched.shuffle
: (Optional.) IfTrue
, the file names will be shuffled randomly. Defaults toTrue
.seed
: (Optional.) Atf.int64
scalartf.Tensor
, representing the random seed that will be used to create the distribution. Seetf.set_random_seed
for behavior.
Returns:
Dataset: A Dataset
of strings corresponding to file names.
tf.data.TextLineDataset.make_initializable_iterator
make_initializable_iterator(shared_name=None)
Creates an Iterator
for enumerating the elements of this dataset.
dataset = ...
iterator = dataset.make_initializable_iterator()
# ...
sess.run(iterator.initializer)
Args:
shared_name
: (Optional.) If non-empty, the returned iterator will be shared under the given name across multiple sessions that share the same devices (e.g. when using a remote server).
Returns:
An Iterator
over the elements of this dataset.
Raises:
RuntimeError
: If eager execution is enabled.
tf.data.TextLineDataset.make_one_shot_iterator
make_one_shot_iterator()
Creates an Iterator
for enumerating the elements of this dataset.
Returns:
An Iterator
over the elements of this dataset.
tf.data.TextLineDataset.map
map(
map_func,
num_parallel_calls=None
)
Maps map_func
across the elements of this dataset.
This transformation applies map_func
to each element of this dataset, and
returns a new dataset containing the transformed elements, in the same
order as they appeared in the input.
For example:
# NOTE: The following examples use `{ ... }` to represent the
# contents of a dataset.
a = { 1, 2, 3, 4, 5 }
a.map(lambda x: x + 1) = { 2, 3, 4, 5, 6 }
The input signature of map_func
is determined by the structure of each
element in this dataset. For example:
# Each element is a <a href="../../tf/Tensor"><code>tf.Tensor</code></a> object.
a = { 1, 2, 3, 4, 5 }
# `map_func` takes a single argument of type <a href="../../tf/Tensor"><code>tf.Tensor</code></a> with the same
# shape and dtype.
result = a.map(lambda x: ...)
# Each element is a tuple containing two <a href="../../tf/Tensor"><code>tf.Tensor</code></a> objects.
b = { (1, "foo"), (2, "bar"), (3, "baz") }
# `map_func` takes two arguments of type <a href="../../tf/Tensor"><code>tf.Tensor</code></a>.
result = b.map(lambda x_int, y_str: ...)
# Each element is a dictionary mapping strings to <a href="../../tf/Tensor"><code>tf.Tensor</code></a> objects.
c = { {"a": 1, "b": "foo"}, {"a": 2, "b": "bar"}, {"a": 3, "b": "baz"} }
# `map_func` takes a single argument of type `dict` with the same keys as
# the elements.
result = c.map(lambda d: ...)
The value or values returned by map_func
determine the structure of each
element in the returned dataset.
# `map_func` returns a scalar <a href="../../tf/Tensor"><code>tf.Tensor</code></a> of type <a href="../../tf/dtypes#float32"><code>tf.float32</code></a>.
def f(...):
return tf.constant(37.0)
result = dataset.map(f)
result.output_classes == tf.Tensor
result.output_types == tf.float32
result.output_shapes == [] # scalar
# `map_func` returns two <a href="../../tf/Tensor"><code>tf.Tensor</code></a> objects.
def g(...):
return tf.constant(37.0), tf.constant(["Foo", "Bar", "Baz"])
result = dataset.map(g)
result.output_classes == (tf.Tensor, tf.Tensor)
result.output_types == (tf.float32, tf.string)
result.output_shapes == ([], [3])
# Python primitives, lists, and NumPy arrays are implicitly converted to
# <a href="../../tf/Tensor"><code>tf.Tensor</code></a>.
def h(...):
return 37.0, ["Foo", "Bar", "Baz"], np.array([1.0, 2.0] dtype=np.float64)
result = dataset.map(h)
result.output_classes == (tf.Tensor, tf.Tensor, tf.Tensor)
result.output_types == (tf.float32, tf.string, tf.float64)
result.output_shapes == ([], [3], [2])
# `map_func` can return nested structures.
def i(...):
return {"a": 37.0, "b": [42, 16]}, "foo"
result.output_classes == ({"a": tf.Tensor, "b": tf.Tensor}, tf.Tensor)
result.output_types == ({"a": tf.float32, "b": tf.int32}, tf.string)
result.output_shapes == ({"a": [], "b": [2]}, [])
In addition to tf.Tensor
objects, map_func
can accept as arguments and
return tf.SparseTensor
objects.
Args:
map_func
: A function mapping a nested structure of tensors (having shapes and types defined byself.output_shapes
andself.output_types
) to another nested structure of tensors.num_parallel_calls
: (Optional.) Atf.int32
scalartf.Tensor
, representing the number elements to process in parallel. If not specified, elements will be processed sequentially. If the valuetf.data.experimental.AUTOTUNE
is used, then the number of parallel calls is set dynamically based on available CPU.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.options
options()
Returns the options for this dataset and its inputs.
Returns:
A tf.data.Options
object representing the dataset options.
tf.data.TextLineDataset.padded_batch
padded_batch(
batch_size,
padded_shapes,
padding_values=None,
drop_remainder=False
)
Combines consecutive elements of this dataset into padded batches.
This transformation combines multiple consecutive elements of the input dataset into a single element.
Like tf.data.Dataset.batch
, the tensors in the resulting element will
have an additional outer dimension, which will be batch_size
(or
N % batch_size
for the last element if batch_size
does not divide the
number of input elements N
evenly and drop_remainder
is False
). If
your program depends on the batches having the same outer dimension, you
should set the drop_remainder
argument to True
to prevent the smaller
batch from being produced.
Unlike tf.data.Dataset.batch
, the input elements to be batched may have
different shapes, and this transformation will pad each component to the
respective shape in padding_shapes
. The padding_shapes
argument
determines the resulting shape for each dimension of each component in an
output element:
- If the dimension is a constant (e.g.
tf.Dimension(37)
), the component will be padded out to that length in that dimension. - If the dimension is unknown (e.g.
tf.Dimension(None)
), the component will be padded out to the maximum length of all elements in that dimension.
See also tf.data.experimental.dense_to_sparse_batch
, which combines
elements that may have different shapes into a tf.SparseTensor
.
Args:
batch_size
: Atf.int64
scalartf.Tensor
, representing the number of consecutive elements of this dataset to combine in a single batch.padded_shapes
: A nested structure oftf.TensorShape
ortf.int64
vector tensor-like objects representing the shape to which the respective component of each input element should be padded prior to batching. Any unknown dimensions (e.g.tf.Dimension(None)
in atf.TensorShape
or-1
in a tensor-like object) will be padded to the maximum size of that dimension in each batch.padding_values
: (Optional.) A nested structure of scalar-shapedtf.Tensor
, representing the padding values to use for the respective components. Defaults are0
for numeric types and the empty string for string types.drop_remainder
: (Optional.) Atf.bool
scalartf.Tensor
, representing whether the last batch should be dropped in the case it has fewer thanbatch_size
elements; the default behavior is not to drop the smaller batch.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.prefetch
prefetch(buffer_size)
Creates a Dataset
that prefetches elements from this dataset.
Args:
buffer_size
: Atf.int64
scalartf.Tensor
, representing the maximum number of elements that will be buffered when prefetching.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.range
range(*args)
Creates a Dataset
of a step-separated range of values.
For example:
Dataset.range(5) == [0, 1, 2, 3, 4]
Dataset.range(2, 5) == [2, 3, 4]
Dataset.range(1, 5, 2) == [1, 3]
Dataset.range(1, 5, -2) == []
Dataset.range(5, 1) == []
Dataset.range(5, 1, -2) == [5, 3]
Args:
*args
: follows the same semantics as python's xrange. len(args) == 1 -> start = 0, stop = args[0], step = 1 len(args) == 2 -> start = args[0], stop = args[1], step = 1 len(args) == 3 -> start = args[0], stop = args[1, stop = args[2]
Returns:
Dataset
: ARangeDataset
.
Raises:
ValueError
: if len(args) == 0.
tf.data.TextLineDataset.reduce
reduce(
initial_state,
reduce_func
)
Reduces the input dataset to a single element.
The transformation calls reduce_func
successively on every element of
the input dataset until the dataset is exhausted, aggregating information in
its internal state. The initial_state
argument is used for the initial
state and the final state is returned as the result.
For example:
- tf.data.Dataset.range(5).reduce(np.int64(0), lambda x, _: x + 1)
produces 5
- tf.data.Dataset.range(5).reduce(np.int64(0), lambda x, y: x + y)
produces 10
Args:
initial_state
: A nested structure of tensors, representing the initial state of the transformation.reduce_func
: A function that maps(old_state, input_element)
tonew_state
. It must take two arguments and return a nested structure of tensors. The structure ofnew_state
must match the structure ofinitial_state
.
Returns:
A nested structure of tf.Tensor
objects, corresponding to the final
state of the transformation.
tf.data.TextLineDataset.repeat
repeat(count=None)
Repeats this dataset count
times.
NOTE: If this dataset is a function of global state (e.g. a random number generator), then different repetitions may produce different elements.
Args:
count
: (Optional.) Atf.int64
scalartf.Tensor
, representing the number of times the dataset should be repeated. The default behavior (ifcount
isNone
or-1
) is for the dataset be repeated indefinitely.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.shard
shard(
num_shards,
index
)
Creates a Dataset
that includes only 1/num_shards
of this dataset. (deprecated)
This dataset operator is very useful when running distributed training, as it allows each worker to read a unique subset.
When reading a single input file, you can skip elements as follows:
d = tf.data.TFRecordDataset(FLAGS.input_file)
d = d.shard(FLAGS.num_workers, FLAGS.worker_index)
d = d.repeat(FLAGS.num_epochs)
d = d.shuffle(FLAGS.shuffle_buffer_size)
d = d.map(parser_fn, num_parallel_calls=FLAGS.num_map_threads)
Important caveats:
- Be sure to shard before you use any randomizing operator (such as shuffle).
- Generally it is best if the shard operator is used early in the dataset pipeline. For example, when reading from a set of TFRecord files, shard before converting the dataset to input samples. This avoids reading every file on every worker. The following is an example of an efficient sharding strategy within a complete pipeline:
d = Dataset.list_files(FLAGS.pattern)
d = d.shard(FLAGS.num_workers, FLAGS.worker_index)
d = d.repeat(FLAGS.num_epochs)
d = d.shuffle(FLAGS.shuffle_buffer_size)
d = d.interleave(tf.data.TFRecordDataset,
cycle_length=FLAGS.num_readers, block_length=1)
d = d.map(parser_fn, num_parallel_calls=FLAGS.num_map_threads)
Args:
num_shards
: Atf.int64
scalartf.Tensor
, representing the number of shards operating in parallel.index
: Atf.int64
scalartf.Tensor
, representing the worker index.
Returns:
Dataset
: ADataset
.
Raises:
ValueError
: ifnum_shards
orindex
are illegal values. Note: error checking is done on a best-effort basis, and errors aren't guaranteed to be caught upon dataset creation. (e.g. providing in a placeholder tensor bypasses the early checking, and will instead result in an error during a session.run call.)
tf.data.TextLineDataset.shuffle
shuffle(
buffer_size,
seed=None,
reshuffle_each_iteration=None
)
Randomly shuffles the elements of this dataset.
This dataset fills a buffer with buffer_size
elements, then randomly
samples elements from this buffer, replacing the selected elements with new
elements. For perfect shuffling, a buffer size greater than or equal to the
full size of the dataset is required.
Args:
buffer_size
: Atf.int64
scalartf.Tensor
, representing the number of elements from this dataset from which the new dataset will sample.seed
: (Optional.) Atf.int64
scalartf.Tensor
, representing the random seed that will be used to create the distribution. Seetf.set_random_seed
for behavior.reshuffle_each_iteration
: (Optional.) A boolean, which if true indicates that the dataset should be pseudorandomly reshuffled each time it is iterated over. (Defaults toTrue
.)
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.skip
skip(count)
Creates a Dataset
that skips count
elements from this dataset.
Args:
count
: Atf.int64
scalartf.Tensor
, representing the number of elements of this dataset that should be skipped to form the new dataset. Ifcount
is greater than the size of this dataset, the new dataset will contain no elements. Ifcount
is -1, skips the entire dataset.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.take
take(count)
Creates a Dataset
with at most count
elements from this dataset.
Args:
count
: Atf.int64
scalartf.Tensor
, representing the number of elements of this dataset that should be taken to form the new dataset. Ifcount
is -1, or ifcount
is greater than the size of this dataset, the new dataset will contain all elements of this dataset.
Returns:
Dataset
: ADataset
.
tf.data.TextLineDataset.window
window(
size,
shift=None,
stride=1,
drop_remainder=False
)
Combines input elements into a dataset of windows.
Each window is a dataset itself and contains size
elements (or
possibly fewer if there are not enough input elements to fill the window
and drop_remainder
evaluates to false).
The stride
argument determines the stride of the input elements,
and the shift
argument determines the shift of the window.
For example:
- tf.data.Dataset.range(7).window(2)
produces
{ {0, 1}, {2, 3}, {4, 5}, {6}}
- tf.data.Dataset.range(7).window(3, 2, 1, True)
produces
{ {0, 1, 2}, {2, 3, 4}, {4, 5, 6}}
- tf.data.Dataset.range(7).window(3, 1, 2, True)
produces
{ {0, 2, 4}, {1, 3, 5}, {2, 4, 6}}
Args:
size
: Atf.int64
scalartf.Tensor
, representing the number of elements of the input dataset to combine into a window.shift
: (Optional.) Atf.int64
scalartf.Tensor
, representing the forward shift of the sliding window in each iteration. Defaults tosize
.stride
: (Optional.) Atf.int64
scalartf.Tensor
, representing the stride of the input elements in the sliding window.drop_remainder
: (Optional.) Atf.bool
scalartf.Tensor
, representing whether a window should be dropped in case its size is smaller thanwindow_size
.
Returns:
Dataset
: ADataset
of windows, each of which is a nestedDataset
with the same structure as this dataset, but a finite subsequence of its elements.
tf.data.TextLineDataset.with_options
with_options(options)
Returns a new tf.data.Dataset
with the given options set.
The options are "global" in the sense they apply to the entire dataset. If options are set multiple times, they are merged as long as different options do not use different non-default values.
Args:
options
: Atf.data.Options
that identifies the options the use.
Returns:
Dataset
: ADataset
with the given options.
Raises:
ValueError
: when an option is set more than once to a non-default value
tf.data.TextLineDataset.zip
zip(datasets)
Creates a Dataset
by zipping together the given datasets.
This method has similar semantics to the built-in zip()
function
in Python, with the main difference being that the datasets
argument can be an arbitrary nested structure of Dataset
objects.
For example:
# NOTE: The following examples use `{ ... }` to represent the
# contents of a dataset.
a = { 1, 2, 3 }
b = { 4, 5, 6 }
c = { (7, 8), (9, 10), (11, 12) }
d = { 13, 14 }
# The nested structure of the `datasets` argument determines the
# structure of elements in the resulting dataset.
Dataset.zip((a, b)) == { (1, 4), (2, 5), (3, 6) }
Dataset.zip((b, a)) == { (4, 1), (5, 2), (6, 3) }
# The `datasets` argument may contain an arbitrary number of
# datasets.
Dataset.zip((a, b, c)) == { (1, 4, (7, 8)),
(2, 5, (9, 10)),
(3, 6, (11, 12)) }
# The number of elements in the resulting dataset is the same as
# the size of the smallest dataset in `datasets`.
Dataset.zip((a, d)) == { (1, 13), (2, 14) }
Args:
datasets
: A nested structure of datasets.
Returns:
Dataset
: ADataset
.