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dataset.py
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dataset.py
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# Copyright (c) 2020 PaddlePaddle 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
# limitations under the License.
from __future__ import print_function
import paddle
from .. import framework
__all__ = [
"Dataset", "IterableDataset", "TensorDataset", "ComposeDataset",
"ChainDataset", "random_split", "Subset"
]
class Dataset(object):
"""
An abstract class to encapsulate methods and behaviors of datasets.
All datasets in map-style(dataset samples can be get by a given key)
should be a subclass of `paddle.io.Dataset`. All subclasses should
implement following methods:
:code:`__getitem__`: get sample from dataset with a given index. This
method is required by reading dataset sample in :code:`paddle.io.DataLoader`.
:code:`__len__`: return dataset sample number. This method is required
by some implements of :code:`paddle.io.BatchSampler`
see :code:`paddle.io.DataLoader`.
Examples:
.. code-block:: python
import numpy as np
from paddle.io import Dataset
# define a random dataset
class RandomDataset(Dataset):
def __init__(self, num_samples):
self.num_samples = num_samples
def __getitem__(self, idx):
image = np.random.random([784]).astype('float32')
label = np.random.randint(0, 9, (1, )).astype('int64')
return image, label
def __len__(self):
return self.num_samples
dataset = RandomDataset(10)
for i in range(len(dataset)):
print(dataset[i])
"""
def __init__(self):
pass
def __getitem__(self, idx):
raise NotImplementedError("'{}' not implement in class "\
"{}".format('__getitem__', self.__class__.__name__))
def __len__(self):
raise NotImplementedError("'{}' not implement in class "\
"{}".format('__len__', self.__class__.__name__))
class IterableDataset(Dataset):
"""
An abstract class to encapsulate methods and behaviors of iterable datasets.
All datasets in iterable-style (can only get sample one by one sequentially, like
a Python iterator) should be a subclass of `paddle.io.IterableDataset`. All subclasses should
implement following methods:
:code:`__iter__`: yield sample sequentially. This method is required by reading dataset sample in :code:`paddle.io.DataLoader`.
.. note::
do not implement :code:`__getitem__` and :code:`__len__` in IterableDataset, should not be called either.
see :code:`paddle.io.DataLoader`.
Examples:
.. code-block:: python
import numpy as np
from paddle.io import IterableDataset
# define a random dataset
class RandomDataset(IterableDataset):
def __init__(self, num_samples):
self.num_samples = num_samples
def __iter__(self):
for i in range(self.num_samples):
image = np.random.random([784]).astype('float32')
label = np.random.randint(0, 9, (1, )).astype('int64')
yield image, label
dataset = RandomDataset(10)
for img, lbl in dataset:
print(img, lbl)
When :attr:`num_workers > 0`, each worker has a different copy of the dataset object and
will yield whole dataset samples, which means samples in dataset will be repeated in
:attr:`num_workers` times. If it is required for each sample to yield only once, there
are two methods to configure different copy in each worker process to avoid duplicate data
among workers as follows. In both the methods, worker information that can be getted in
a worker process by `paddle.io.get_worker_info` will be needed.
Example 1: splitting data copy in each worker in :code:`__iter__`
.. code-block:: python
import math
import paddle
import numpy as np
from paddle.io import IterableDataset, DataLoader, get_worker_info
class SplitedIterableDataset(IterableDataset):
def __init__(self, start, end):
self.start = start
self.end = end
def __iter__(self):
worker_info = get_worker_info()
if worker_info is None:
iter_start = self.start
iter_end = self.end
else:
per_worker = int(
math.ceil((self.end - self.start) / float(
worker_info.num_workers)))
worker_id = worker_info.id
iter_start = self.start + worker_id * per_worker
iter_end = min(iter_start + per_worker, self.end)
for i in range(iter_start, iter_end):
yield np.array([i])
dataset = SplitedIterableDataset(start=2, end=9)
dataloader = DataLoader(
dataset,
num_workers=2,
batch_size=1,
drop_last=True)
for data in dataloader:
print(data)
# outputs: [2, 5, 3, 6, 4, 7]
Example 2: splitting data copy in each worker by :code:`worker_init_fn`
.. code-block:: python
import math
import paddle
import numpy as np
from paddle.io import IterableDataset, DataLoader, get_worker_info
class RangeIterableDataset(IterableDataset):
def __init__(self, start, end):
self.start = start
self.end = end
def __iter__(self):
for i in range(self.start, self.end):
yield np.array([i])
dataset = RangeIterableDataset(start=2, end=9)
def worker_init_fn(worker_id):
worker_info = get_worker_info()
dataset = worker_info.dataset
start = dataset.start
end = dataset.end
num_per_worker = int(
math.ceil((end - start) / float(worker_info.num_workers)))
worker_id = worker_info.id
dataset.start = start + worker_id * num_per_worker
dataset.end = min(dataset.start + num_per_worker, end)
dataloader = DataLoader(
dataset,
num_workers=2,
batch_size=1,
drop_last=True,
worker_init_fn=worker_init_fn)
for data in dataloader:
print(data)
# outputs: [2, 5, 3, 6, 4, 7]
"""
def __init__(self):
pass
def __iter__(self):
raise NotImplementedError("'{}' not implement in class "\
"{}".format('__iter__', self.__class__.__name__))
def __getitem__(self, idx):
raise RuntimeError("'{}' should not be called for IterableDataset" \
"{}".format('__getitem__', self.__class__.__name__))
def __len__(self):
raise RuntimeError("'{}' should not be called for IterableDataset" \
"{}".format('__len__', self.__class__.__name__))
class TensorDataset(Dataset):
"""
Dataset defined by a list of tensors.
Each tensor should be in shape of [N, ...], while N is the sample number,
and ecah tensor contains a field of sample, :code:`TensorDataset` retrieve
each sample by indexing tensors in the 1st dimension.
Args:
tensors(list|tuple): A list/tuple of tensors with same shape in the 1st dimension.
Returns:
Dataset: a Dataset instance wrapping tensors.
Examples:
.. code-block:: python
import numpy as np
import paddle
from paddle.io import TensorDataset
input_np = np.random.random([2, 3, 4]).astype('float32')
input = paddle.to_tensor(input_np)
label_np = np.random.random([2, 1]).astype('int32')
label = paddle.to_tensor(label_np)
dataset = TensorDataset([input, label])
for i in range(len(dataset)):
input, label = dataset[i]
print(input, label)
"""
def __init__(self, tensors):
if not framework.in_dygraph_mode():
raise RuntimeError(
"TensorDataset con only be used in imperative mode")
assert all([tensor.shape[0] == tensors[0].shape[0] for tensor in tensors]), \
"tensors not have same shape of the 1st dimension"
self.tensors = tensors
def __getitem__(self, index):
return tuple(tensor[index] for tensor in self.tensors)
def __len__(self):
return self.tensors[0].shape[0]
def to_list(value):
if value is None:
return value
if isinstance(value, (list, tuple)):
return list(value)
return [value]
class ComposeDataset(Dataset):
"""
A Dataset which composes fields of multiple datasets.
This dataset is used for composing fileds of multiple map-style
datasets of same length.
Args:
datasets(list of Dataset): List of datasets to be composed.
Returns:
Dataset: A Dataset which composes fields of multiple datasets.
Examples:
.. code-block:: python
import numpy as np
import paddle
from paddle.io import Dataset, ComposeDataset
# define a random dataset
class RandomDataset(Dataset):
def __init__(self, num_samples):
self.num_samples = num_samples
def __getitem__(self, idx):
image = np.random.random([32]).astype('float32')
label = np.random.randint(0, 9, (1, )).astype('int64')
return image, label
def __len__(self):
return self.num_samples
dataset = ComposeDataset([RandomDataset(10), RandomDataset(10)])
for i in range(len(dataset)):
image1, label1, image2, label2 = dataset[i]
print(image1)
print(label1)
print(image2)
print(label2)
"""
def __init__(self, datasets):
self.datasets = list(datasets)
assert len(self.datasets) > 0, "input datasets shoule not be empty"
for i, dataset in enumerate(self.datasets):
assert isinstance(dataset, Dataset), \
"each input dataset should be paddle.io.Dataset"
assert not isinstance(dataset, IterableDataset), \
"paddle.io.IterableDataset not supported"
if i > 0:
assert len(dataset) == len(self.datasets[i-1]), \
"lengths of datasets should be same"
def __len__(self):
return len(self.datasets[0])
def __getitem__(self, idx):
sample = []
for dataset in self.datasets:
sample.extend(to_list(dataset[idx]))
return tuple(sample)
class ChainDataset(IterableDataset):
"""
A Dataset which chains multiple iterable-tyle datasets.
This dataset is used for assembling multiple datasets which should
be :code:`paddle.io.IterableDataset`.
Args:
datasets(list of Dataset): List of datasets to be chainned.
Returns:
Dataset: A Dataset which chains fields of multiple datasets.
Examples:
.. code-block:: python
import numpy as np
import paddle
from paddle.io import IterableDataset, ChainDataset
# define a random dataset
class RandomDataset(IterableDataset):
def __init__(self, num_samples):
self.num_samples = num_samples
def __iter__(self):
for i in range(10):
image = np.random.random([32]).astype('float32')
label = np.random.randint(0, 9, (1, )).astype('int64')
yield image, label
dataset = ChainDataset([RandomDataset(10), RandomDataset(10)])
for image, label in iter(dataset):
print(image, label)
"""
def __init__(self, datasets):
self.datasets = list(datasets)
assert len(self.datasets) > 0, "input datasets shoule not be empty"
for i, dataset in enumerate(self.datasets):
assert isinstance(dataset, IterableDataset), \
"ChainDataset only support paddle.io.IterableDataset"
def __iter__(self):
for dataset in self.datasets:
for sample in dataset:
yield sample
class Subset(Dataset):
"""
Subset of a dataset at specified indices.
Args:
dataset (Dataset): The whole Dataset.
indices (sequence): Indices in the whole set selected for subset.
Returns:
Dataset: A Dataset which is the subset of the original dataset.
Example code:
.. code-block:: python
import paddle
from paddle.io import Subset
# example 1:
a = paddle.io.Subset(dataset=range(1, 4), indices=[0, 2])
print(list(a))
# [1, 3]
# example 2:
b = paddle.io.Subset(dataset=range(1, 4), indices=[1, 1])
print(list(b))
# [2, 2]
"""
def __init__(self, dataset, indices):
self.dataset = dataset
self.indices = indices
def __getitem__(self, idx):
return self.dataset[self.indices[idx]]
def __len__(self):
return len(self.indices)
def random_split(dataset, lengths, generator=None):
"""
Randomly split a dataset into non-overlapping new datasets of given lengths.
Optionally fix the generator for reproducible results, e.g.:
Args:
dataset (Dataset): Dataset to be split
lengths (sequence): lengths of splits to be produced
generator (Generator, optional): Generator used for the random permutation. Default is None then the DefaultGenerator is used in manual_seed().
Returns:
Datasets: A list of subset Datasets, which are the non-overlapping subsets of the original Dataset.
Example code:
.. code-block:: python
import paddle
from paddle.io import random_split
a_list = paddle.io.random_split(range(10), [3, 7])
print(len(a_list))
# 2
for idx, v in enumerate(a_list[0]):
print(idx, v)
# output of the first subset
# 0 1
# 1 3
# 2 9
for idx, v in enumerate(a_list[1]):
print(idx, v)
# output of the second subset
# 0 5
# 1 7
# 2 8
# 3 6
# 4 0
# 5 2
# 6 4
"""
# Cannot verify that dataset is Sized
if sum(lengths) != len(dataset): # type: ignore
raise ValueError(
"Sum of input lengths does not equal the length of the input dataset!"
)
# TODO(@Joejiong): support Variable or Tensor type with .tolist class member function.
# For example var.item() and var.tolist()
indices = paddle.randperm(sum(lengths)).numpy().tolist()
return [
Subset(dataset, indices[offset - length:offset])
for offset, length in zip(_accumulate(lengths), lengths)
]
def _accumulate(iterable, fn=lambda x, y: x + y):
"""
Return running totals
Args:
iterable: any iterable object for example dataset.
y (x): one element in the iterable object.
fn (x, y): Defaults to lambdax.
Yields:
yields total from beginning iterator to current iterator.
Example code:
.. code-block:: python
_accumulate([1,2,3,4,5]) --> 1 3 6 10 15
_accumulate([1,2,3,4,5], operator.mul) --> 1 2 6 24 120
"""
it = iter(iterable)
try:
total = next(it)
except StopIteration:
return
yield total
for element in it:
total = fn(total, element)
yield total