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Base object for fitting to a sequence of data, such as a dataset.

Every `Sequence`

must implement the `__getitem__`

and the `__len__`

methods. If you want to modify your dataset between epochs you may implement `on_epoch_end`

. The method `__getitem__`

should return a complete batch.

`Sequence`

are a safer way to do multiprocessing. This structure guarantees that the network will only train once on each sample per epoch which is not the case with generators.

from skimage.io import imread from skimage.transform import resize import numpy as np import math # Here, `x_set` is list of path to the images # and `y_set` are the associated classes. class CIFAR10Sequence(Sequence): def __init__(self, x_set, y_set, batch_size): self.x, self.y = x_set, y_set self.batch_size = batch_size def __len__(self): return math.ceil(len(self.x) / self.batch_size) def __getitem__(self, idx): batch_x = self.x[idx * self.batch_size:(idx + 1) * self.batch_size] batch_y = self.y[idx * self.batch_size:(idx + 1) * self.batch_size] return np.array([ resize(imread(file_name), (200, 200)) for file_name in batch_x]), np.array(batch_y)

`on_epoch_end`

on_epoch_end()

Method called at the end of every epoch.

`__getitem__`

__getitem__( index )

Gets batch at position `index`

.

Arguments | |
---|---|

`index` | position of the batch in the Sequence. |

Returns | |
---|---|

A batch |

`__iter__`

__iter__()

Create a generator that iterate over the Sequence.

`__len__`

__len__()

Number of batch in the Sequence.

Returns | |
---|---|

The number of batches in the Sequence. |

© 2020 The TensorFlow Authors. All rights reserved.

Licensed under the Creative Commons Attribution License 3.0.

Code samples licensed under the Apache 2.0 License.

https://www.tensorflow.org/versions/r1.15/api_docs/python/tf/keras/utils/Sequence