433 lines
19 KiB
Python
433 lines
19 KiB
Python
# -*- coding: utf-8 -*-
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"""Data providers.
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This module provides classes for loading datasets and iterating over batches of
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data points.
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"""
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import pickle
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import gzip
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import numpy as np
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import os
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from mlp import DEFAULT_SEED
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class DataProvider(object):
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"""Generic data provider."""
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def __init__(self, inputs, targets, batch_size, max_num_batches=-1,
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shuffle_order=True, rng=None, smooth_labels=False):
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"""Create a new data provider object.
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Args:
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inputs (ndarray): Array of data input features of shape
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(num_data, input_dim).
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targets (ndarray): Array of data output targets of shape
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(num_data, output_dim) or (num_data,) if output_dim == 1.
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batch_size (int): Number of data points to include in each batch.
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max_num_batches (int): Maximum number of batches to iterate over
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in an epoch. If `max_num_batches * batch_size > num_data` then
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only as many batches as the data can be split into will be
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used. If set to -1 all of the data will be used.
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shuffle_order (bool): Whether to randomly permute the order of
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the data before each epoch.
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rng (RandomState): A seeded random number generator.
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smooth_labels (bool): turn on label smoothing
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"""
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self.inputs = inputs
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self.targets = targets
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if batch_size < 1:
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raise ValueError('batch_size must be >= 1')
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self._batch_size = batch_size
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if max_num_batches == 0 or max_num_batches < -1:
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raise ValueError('max_num_batches must be -1 or > 0')
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self._max_num_batches = max_num_batches
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self._update_num_batches()
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self.shuffle_order = shuffle_order
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self._current_order = np.arange(inputs.shape[0])
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if rng is None:
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rng = np.random.RandomState(DEFAULT_SEED)
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self.rng = rng
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self.smooth_labels = smooth_labels
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self.new_epoch()
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@property
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def batch_size(self):
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"""Number of data points to include in each batch."""
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return self._batch_size
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@batch_size.setter
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def batch_size(self, value):
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if value < 1:
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raise ValueError('batch_size must be >= 1')
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self._batch_size = value
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self._update_num_batches()
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@property
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def max_num_batches(self):
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"""Maximum number of batches to iterate over in an epoch."""
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return self._max_num_batches
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@max_num_batches.setter
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def max_num_batches(self, value):
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if value == 0 or value < -1:
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raise ValueError('max_num_batches must be -1 or > 0')
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self._max_num_batches = value
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self._update_num_batches()
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def _update_num_batches(self):
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"""Updates number of batches to iterate over."""
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# maximum possible number of batches is equal to number of whole times
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# batch_size divides in to the number of data points which can be
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# found using integer division
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possible_num_batches = self.inputs.shape[0] // self.batch_size
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if self.max_num_batches == -1:
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self.num_batches = possible_num_batches
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else:
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self.num_batches = min(self.max_num_batches, possible_num_batches)
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def __iter__(self):
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"""Implements Python iterator interface.
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This should return an object implementing a `next` method which steps
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through a sequence returning one element at a time and raising
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`StopIteration` when at the end of the sequence. Here the object
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returned is the DataProvider itself.
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"""
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return self
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def new_epoch(self):
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"""Starts a new epoch (pass through data), possibly shuffling first."""
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self._curr_batch = 0
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if self.shuffle_order:
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self.shuffle()
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def __next__(self):
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return self.next()
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def reset(self):
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"""Resets the provider to the initial state."""
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inv_perm = np.argsort(self._current_order)
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self._current_order = self._current_order[inv_perm]
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self.inputs = self.inputs[inv_perm]
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self.targets = self.targets[inv_perm]
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self.new_epoch()
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def shuffle(self):
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"""Randomly shuffles order of data."""
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perm = self.rng.permutation(self.inputs.shape[0])
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self._current_order = self._current_order[perm]
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self.inputs = self.inputs[perm]
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self.targets = self.targets[perm]
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def next(self):
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"""Returns next data batch or raises `StopIteration` if at end."""
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if self._curr_batch + 1 > self.num_batches:
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# no more batches in current iteration through data set so start
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# new epoch ready for another pass and indicate iteration is at end
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self.new_epoch()
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raise StopIteration()
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# create an index slice corresponding to current batch number
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batch_slice = slice(self._curr_batch * self.batch_size,
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(self._curr_batch + 1) * self.batch_size)
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inputs_batch = self.inputs[batch_slice]
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targets_batch = self.targets[batch_slice]
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self._curr_batch += 1
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return inputs_batch, targets_batch
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class MNISTDataProvider(DataProvider):
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"""Data provider for MNIST handwritten digit images."""
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def __init__(self, which_set='train', batch_size=100, max_num_batches=-1,
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shuffle_order=True, rng=None, smooth_labels=False):
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"""Create a new MNIST data provider object.
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Args:
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which_set: One of 'train', 'valid' or 'eval'. Determines which
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portion of the MNIST data this object should provide.
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batch_size (int): Number of data points to include in each batch.
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max_num_batches (int): Maximum number of batches to iterate over
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in an epoch. If `max_num_batches * batch_size > num_data` then
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only as many batches as the data can be split into will be
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used. If set to -1 all of the data will be used.
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shuffle_order (bool): Whether to randomly permute the order of
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the data before each epoch.
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rng (RandomState): A seeded random number generator.
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smooth_labels (bool): enable/disable label smoothing
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"""
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# check a valid which_set was provided
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assert which_set in ['train', 'valid', 'test'], (
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'Expected which_set to be either train, valid or eval. '
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'Got {0}'.format(which_set)
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)
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self.which_set = which_set
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self.num_classes = 10
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# construct path to data using os.path.join to ensure the correct path
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# separator for the current platform / OS is used
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# MLP_DATA_DIR environment variable should point to the data directory
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data_path = os.path.join(
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os.environ['MLP_DATA_DIR'], 'mnist-{0}.npz'.format(which_set))
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assert os.path.isfile(data_path), (
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'Data file does not exist at expected path: ' + data_path
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)
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# load data from compressed numpy file
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loaded = np.load(data_path)
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inputs, targets = loaded['inputs'], loaded['targets']
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inputs = inputs.astype(np.float32)
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# pass the loaded data to the parent class __init__
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super(MNISTDataProvider, self).__init__(
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inputs, targets, batch_size, max_num_batches, shuffle_order, rng, smooth_labels)
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def next(self):
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"""Returns next data batch or raises `StopIteration` if at end."""
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inputs_batch, targets_batch = super(MNISTDataProvider, self).next()
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return inputs_batch, self.to_one_of_k(targets_batch)
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def to_one_of_k(self, int_targets):
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"""Converts integer coded class target to 1 of K coded targets.
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Args:
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int_targets (ndarray): Array of integer coded class targets (i.e.
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where an integer from 0 to `num_classes` - 1 is used to
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indicate which is the correct class). This should be of shape
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(num_data,).
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Returns:
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Array of 1 of K coded targets i.e. an array of shape
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(num_data, num_classes) where for each row all elements are equal
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to zero except for the column corresponding to the correct class
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which is equal to one.
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"""
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one_of_k_targets = np.zeros((int_targets.shape[0], self.num_classes))
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one_of_k_targets[range(int_targets.shape[0]), int_targets] = 1
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return one_of_k_targets
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class EMNISTDataProvider(DataProvider):
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"""Data provider for EMNIST handwritten digit images."""
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def __init__(self, which_set='train', batch_size=100, max_num_batches=-1,
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shuffle_order=True, rng=None, smooth_labels=False):
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"""Create a new EMNIST data provider object.
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Args:
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which_set: One of 'train', 'valid' or 'eval'. Determines which
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portion of the EMNIST data this object should provide.
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batch_size (int): Number of data points to include in each batch.
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max_num_batches (int): Maximum number of batches to iterate over
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in an epoch. If `max_num_batches * batch_size > num_data` then
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only as many batches as the data can be split into will be
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used. If set to -1 all of the data will be used.
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shuffle_order (bool): Whether to randomly permute the order of
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the data before each epoch.
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rng (RandomState): A seeded random number generator.
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smooth_labels (bool): enable/disable label smoothing
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"""
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# check a valid which_set was provided
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assert which_set in ['train', 'valid', 'test'], (
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'Expected which_set to be either train, valid or eval. '
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'Got {0}'.format(which_set)
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)
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self.which_set = which_set
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self.num_classes = 47
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# construct path to data using os.path.join to ensure the correct path
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# separator for the current platform / OS is used
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# MLP_DATA_DIR environment variable should point to the data directory
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data_path = os.path.join(
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os.environ['MLP_DATA_DIR'], 'emnist-{0}.npz'.format(which_set))
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assert os.path.isfile(data_path), (
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'Data file does not exist at expected path: ' + data_path
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)
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# load data from compressed numpy file
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loaded = np.load(data_path)
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print(loaded.keys())
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inputs, targets = loaded['inputs'], loaded['targets']
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inputs = inputs.astype(np.float32)
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inputs = np.reshape(inputs, newshape=(-1, 28*28))
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inputs = inputs / 255.0
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# pass the loaded data to the parent class __init__
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super(EMNISTDataProvider, self).__init__(
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inputs, targets, batch_size, max_num_batches, shuffle_order, rng, smooth_labels)
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def next(self):
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"""Returns next data batch or raises `StopIteration` if at end."""
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inputs_batch, targets_batch = super(EMNISTDataProvider, self).next()
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if self.smooth_labels:
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targets_batch_mat = self.label_smoothing(targets_batch)
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else:
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targets_batch_mat = self.to_one_of_k(targets_batch)
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return inputs_batch, targets_batch_mat
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def to_one_of_k(self, int_targets):
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"""Converts integer coded class target to 1 of K coded targets.
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Args:
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int_targets (ndarray): Array of integer coded class targets (i.e.
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where an integer from 0 to `num_classes` - 1 is used to
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indicate which is the correct class). This should be of shape
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(num_data,).
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Returns:
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Array of 1 of K coded targets i.e. an array of shape
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(num_data, num_classes) where for each row all elements are equal
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to zero except for the column corresponding to the correct class
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which is equal to one.
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"""
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one_of_k_targets = np.zeros((int_targets.shape[0], self.num_classes))
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one_of_k_targets[range(int_targets.shape[0]), int_targets] = 1
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return one_of_k_targets
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def label_smoothing(self, int_targets, alpha=0.1):
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"""Converts integer coded class target to 1 of K coded targets with label smoothing.
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Args:
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int_targets (ndarray): Array of integer coded class targets (i.e.
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where an integer from 0 to `num_classes` - 1 is used to
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indicate which is the correct class). This should be of shape
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(num_data,).
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alpha (float): Smoothing factor.
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Returns:
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Array of 1 of K coded targets with label smoothing i.e. an array of shape
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(num_data, num_classes)
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"""
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raise NotImplementedError
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class MetOfficeDataProvider(DataProvider):
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"""South Scotland Met Office weather data provider."""
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def __init__(self, window_size, batch_size=10, max_num_batches=-1,
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shuffle_order=True, rng=None):
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"""Create a new Met Office data provider object.
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Args:
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window_size (int): Size of windows to split weather time series
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data into. The constructed input features will be the first
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`window_size - 1` entries in each window and the target outputs
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the last entry in each window.
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batch_size (int): Number of data points to include in each batch.
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max_num_batches (int): Maximum number of batches to iterate over
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in an epoch. If `max_num_batches * batch_size > num_data` then
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only as many batches as the data can be split into will be
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used. If set to -1 all of the data will be used.
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shuffle_order (bool): Whether to randomly permute the order of
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the data before each epoch.
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rng (RandomState): A seeded random number generator.
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"""
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data_path = os.path.join(
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os.environ['MLP_DATA_DIR'], 'HadSSP_daily_qc.txt')
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assert os.path.isfile(data_path), (
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'Data file does not exist at expected path: ' + data_path
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)
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raw = np.loadtxt(data_path, skiprows=3, usecols=range(2, 32))
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assert window_size > 1, 'window_size must be at least 2.'
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self.window_size = window_size
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# filter out all missing datapoints and flatten to a vector
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filtered = raw[raw >= 0].flatten()
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# normalise data to zero mean, unit standard deviation
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mean = np.mean(filtered)
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std = np.std(filtered)
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normalised = (filtered - mean) / std
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# create a view on to array corresponding to a rolling window
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shape = (normalised.shape[-1] - self.window_size + 1, self.window_size)
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strides = normalised.strides + (normalised.strides[-1],)
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windowed = np.lib.stride_tricks.as_strided(
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normalised, shape=shape, strides=strides)
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# inputs are first (window_size - 1) entries in windows
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inputs = windowed[:, :-1]
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# targets are last entry in windows
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targets = windowed[:, -1]
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super(MetOfficeDataProvider, self).__init__(
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inputs, targets, batch_size, max_num_batches, shuffle_order, rng)
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class CCPPDataProvider(DataProvider):
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def __init__(self, which_set='train', input_dims=None, batch_size=10,
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max_num_batches=-1, shuffle_order=True, rng=None):
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"""Create a new Combined Cycle Power Plant data provider object.
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Args:
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which_set: One of 'train' or 'valid'. Determines which portion of
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data this object should provide.
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input_dims: Which of the four input dimension to use. If `None` all
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are used. If an iterable of integers are provided (consisting
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of a subset of {0, 1, 2, 3}) then only the corresponding
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input dimensions are included.
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batch_size (int): Number of data points to include in each batch.
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max_num_batches (int): Maximum number of batches to iterate over
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in an epoch. If `max_num_batches * batch_size > num_data` then
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only as many batches as the data can be split into will be
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used. If set to -1 all of the data will be used.
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shuffle_order (bool): Whether to randomly permute the order of
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the data before each epoch.
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rng (RandomState): A seeded random number generator.
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"""
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data_path = os.path.join(
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os.environ['MLP_DATA_DIR'], 'ccpp_data.npz')
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assert os.path.isfile(data_path), (
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'Data file does not exist at expected path: ' + data_path
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)
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# check a valid which_set was provided
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assert which_set in ['train', 'valid'], (
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'Expected which_set to be either train or valid '
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'Got {0}'.format(which_set)
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)
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# check input_dims are valid
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if not input_dims is not None:
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input_dims = set(input_dims)
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assert input_dims.issubset({0, 1, 2, 3}), (
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'input_dims should be a subset of {0, 1, 2, 3}'
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)
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loaded = np.load(data_path)
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inputs = loaded[which_set + '_inputs']
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if input_dims is not None:
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inputs = inputs[:, input_dims]
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targets = loaded[which_set + '_targets']
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super(CCPPDataProvider, self).__init__(
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inputs, targets, batch_size, max_num_batches, shuffle_order, rng)
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class AugmentedMNISTDataProvider(MNISTDataProvider):
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"""Data provider for MNIST dataset which randomly transforms images."""
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def __init__(self, which_set='train', batch_size=100, max_num_batches=-1,
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shuffle_order=True, rng=None, transformer=None):
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"""Create a new augmented MNIST data provider object.
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Args:
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which_set: One of 'train', 'valid' or 'test'. Determines which
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portion of the MNIST data this object should provide.
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batch_size (int): Number of data points to include in each batch.
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max_num_batches (int): Maximum number of batches to iterate over
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in an epoch. If `max_num_batches * batch_size > num_data` then
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only as many batches as the data can be split into will be
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used. If set to -1 all of the data will be used.
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shuffle_order (bool): Whether to randomly permute the order of
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the data before each epoch.
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rng (RandomState): A seeded random number generator.
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transformer: Function which takes an `inputs` array of shape
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(batch_size, input_dim) corresponding to a batch of input
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images and a `rng` random number generator object (i.e. a
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call signature `transformer(inputs, rng)`) and applies a
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potentiall random set of transformations to some / all of the
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input images as each new batch is returned when iterating over
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the data provider.
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"""
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super(AugmentedMNISTDataProvider, self).__init__(
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which_set, batch_size, max_num_batches, shuffle_order, rng)
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self.transformer = transformer
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def next(self):
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"""Returns next data batch or raises `StopIteration` if at end."""
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inputs_batch, targets_batch = super(
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AugmentedMNISTDataProvider, self).next()
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transformed_inputs_batch = self.transformer(inputs_batch, self.rng)
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return transformed_inputs_batch, targets_batch
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