Numpy实现深度学习Model

from __future__ import print_function, division
from terminaltables import AsciiTable
import numpy as np
import progressbar
from mlfromscratch.utils import batch_iterator
from mlfromscratch.utils.misc import bar_widgets


class NeuralNetwork():
    """Neural Network. Deep Learning base model.

    Parameters:
    -----------
    optimizer: class
        The weight optimizer that will be used to tune the weights in order of minimizing
        the loss.
    loss: class
        Loss function used to measure the model's performance. SquareLoss or CrossEntropy.
    validation: tuple
        A tuple containing validation data and labels (X, y)
    """
    def __init__(self, optimizer, loss, validation_data=None):
        self.optimizer = optimizer
        self.layers = []
        self.errors = {"training": [], "validation": []}
        self.loss_function = loss()
        self.progressbar = progressbar.ProgressBar(widgets=bar_widgets)

        self.val_set = None
        if validation_data:
            X, y = validation_data
            self.val_set = {"X": X, "y": y}

    def set_trainable(self, trainable):
        """ Method which enables freezing of the weights of the network's layers. """
        for layer in self.layers:
            layer.trainable = trainable

    def add(self, layer):
        """ Method which adds a layer to the neural network """
        # If this is not the first layer added then set the input shape
        # to the output shape of the last added layer
        if self.layers:
            layer.set_input_shape(shape=self.layers[-1].output_shape())

        # If the layer has weights that needs to be initialized 
        if hasattr(layer, 'initialize'):
            layer.initialize(optimizer=self.optimizer)

        # Add layer to the network
        self.layers.append(layer)

    def test_on_batch(self, X, y):
        """ Evaluates the model over a single batch of samples """
        y_pred = self._forward_pass(X, training=False)
        loss = np.mean(self.loss_function.loss(y, y_pred))
        acc = self.loss_function.acc(y, y_pred)

        return loss, acc

    def train_on_batch(self, X, y):
        """ Single gradient update over one batch of samples """
        y_pred = self._forward_pass(X)
        loss = np.mean(self.loss_function.loss(y, y_pred))
        acc = self.loss_function.acc(y, y_pred)
        # Calculate the gradient of the loss function wrt y_pred
        loss_grad = self.loss_function.gradient(y, y_pred)
        # Backpropagate. Update weights
        self._backward_pass(loss_grad=loss_grad)

        return loss, acc

    def fit(self, X, y, n_epochs, batch_size):
        """ Trains the model for a fixed number of epochs """
        for _ in self.progressbar(range(n_epochs)):
            
            batch_error = []
            for X_batch, y_batch in batch_iterator(X, y, batch_size=batch_size):
                loss, _ = self.train_on_batch(X_batch, y_batch)
                batch_error.append(loss)

            self.errors["training"].append(np.mean(batch_error))

            if self.val_set is not None:
                val_loss, _ = self.test_on_batch(self.val_set["X"], self.val_set["y"])
                self.errors["validation"].append(val_loss)

        return self.errors["training"], self.errors["validation"]

    def _forward_pass(self, X, training=True):
        """ Calculate the output of the NN """
        layer_output = X
        for layer in self.layers:
            layer_output = layer.forward_pass(layer_output, training)

        return layer_output

    def _backward_pass(self, loss_grad):
        """ Propagate the gradient 'backwards' and update the weights in each layer """
        for layer in reversed(self.layers):
            loss_grad = layer.backward_pass(loss_grad)

    def summary(self, name="Model Summary"):
        # Print model name
        print (AsciiTable([[name]]).table)
        # Network input shape (first layer's input shape)
        print ("Input Shape: %s" % str(self.layers[0].input_shape))
        # Iterate through network and get each layer's configuration
        table_data = [["Layer Type", "Parameters", "Output Shape"]]
        tot_params = 0
        for layer in self.layers:
            layer_name = layer.layer_name()
            params = layer.parameters()
            out_shape = layer.output_shape()
            table_data.append([layer_name, str(params), str(out_shape)])
            tot_params += params
        # Print network configuration table
        print (AsciiTable(table_data).table)
        print ("Total Parameters: %d\n" % tot_params)

    def predict(self, X):
        """ Use the trained model to predict labels of X """
        return self._forward_pass(X, training=False)


  

 

  
1
  
2
  
3
  
4
  
5
  
6
  
7
  
8
  
9
  
10
  
11
  
12
  
13
  
14
  
15
  
16
  
17
  
18
  
19
  
20
  
21
  
22
  
23
  
24
  
25
  
26
  
27
  
28
  
29
  
30
  
31
  
32
  
33
  
34
  
35
  
36
  
37
  
38
  
39
  
40
  
41
  
42
  
43
  
44
  
45
  
46
  
47
  
48
  
49
  
50
  
51
  
52
  
53
  
54
  
55
  
56
  
57
  
58
  
59
  
60
  
61
  
62
  
63
  
64
  
65
  
66
  
67
  
68
  
69
  
70
  
71
  
72
  
73
  
74
  
75
  
76
  
77
  
78
  
79
  
80
  
81
  
82
  
83
  
84
  
85
  
86
  
87
  
88
  
89
  
90
  
91
  
92
  
93
  
94
  
95
  
96
  
97
  
98
  
99
  
100
  
101
  
102
  
103
  
104
  
105
  
106
  
107
  
108
  
109
  
110
  
111
  
112
  
113
  
114
  
115
  
116
  
117
  
118
  
119
  
120
  
121
  
122
  
123
  
124
 

文章来源: wanghao.blog.csdn.net，作者：AI浩，版权归原作者所有，如需转载，请联系作者。

原文链接：wanghao.blog.csdn.net/article/details/120645441