ajout resnet18

code/resnet18/resnet18.py

+from keras.callbacks import EarlyStopping
+from keras.layers import Dense, Conv2D,  MaxPool2D, Flatten, GlobalAveragePooling2D,  BatchNormalization, Layer, Add
+from keras.models import Sequential
+from keras.models import Model
+import tensorflow as tf
+
+class ResnetBlock(Model):
+    """
+    A standard resnet block.
+    """
+
+    def __init__(self, channels: int, down_sample=False):
+        """
+        channels: same as number of convolution kernels
+        """
+        super().__init__()
+
+        self.__channels = channels
+        self.__down_sample = down_sample
+        self.__strides = [2, 1] if down_sample else [1, 1]
+
+        KERNEL_SIZE = (3, 3)
+        # use He initialization, instead of Xavier (a.k.a 'glorot_uniform' in Keras), as suggested in [2]
+        INIT_SCHEME = "he_normal"
+
+        self.conv_1 = Conv2D(self.__channels, strides=self.__strides[0],
+                             kernel_size=KERNEL_SIZE, padding="same", kernel_initializer=INIT_SCHEME)
+        self.bn_1 = BatchNormalization()
+        self.conv_2 = Conv2D(self.__channels, strides=self.__strides[1],
+                             kernel_size=KERNEL_SIZE, padding="same", kernel_initializer=INIT_SCHEME)
+        self.bn_2 = BatchNormalization()
+        self.merge = Add()
+
+        if self.__down_sample:
+            # perform down sampling using stride of 2, according to [1].
+            self.res_conv = Conv2D(
+                self.__channels, strides=2, kernel_size=(1, 1), kernel_initializer=INIT_SCHEME, padding="same")
+            self.res_bn = BatchNormalization()
+
+    def call(self, inputs):
+        res = inputs
+
+        x = self.conv_1(inputs)
+        x = self.bn_1(x)
+        x = tf.nn.relu(x)
+        x = self.conv_2(x)
+        x = self.bn_2(x)
+
+        if self.__down_sample:
+            res = self.res_conv(res)
+            res = self.res_bn(res)
+
+        # if not perform down sample, then add a shortcut directly
+        x = self.merge([x, res])
+        out = tf.nn.relu(x)
+        return out
+
+
+class ResNet18(Model):
+
+    def __init__(self, num_classes, **kwargs):
+        """
+            num_classes: number of classes in specific classification task.
+        """
+        super().__init__(**kwargs)
+        self.conv_1 = Conv2D(64, (7, 7), strides=2,
+                             padding="same", kernel_initializer="he_normal")
+        self.init_bn = BatchNormalization()
+        self.pool_2 = MaxPool2D(pool_size=(2, 2), strides=2, padding="same")
+        self.res_1_1 = ResnetBlock(64)
+        self.res_1_2 = ResnetBlock(64)
+        self.res_2_1 = ResnetBlock(128, down_sample=True)
+        self.res_2_2 = ResnetBlock(128)
+        self.res_3_1 = ResnetBlock(256, down_sample=True)
+        self.res_3_2 = ResnetBlock(256)
+        self.res_4_1 = ResnetBlock(512, down_sample=True)
+        self.res_4_2 = ResnetBlock(512)
+        self.avg_pool = GlobalAveragePooling2D()
+        self.flat = Flatten()
+        self.fc = Dense(num_classes, activation="softmax")
+
+    def call(self, inputs):
+        out = self.conv_1(inputs)
+        out = self.init_bn(out)
+        out = tf.nn.relu(out)
+        out = self.pool_2(out)
+        for res_block in [self.res_1_1, self.res_1_2, self.res_2_1, self.res_2_2, self.res_3_1, self.res_3_2, self.res_4_1, self.res_4_2]:
+            out = res_block(out)
+        out = self.avg_pool(out)
+        out = self.flat(out)
+        out = self.fc(out)
+        return out

code/resnet18/resnet18_snake.py

+# Réseau inspiré de http://yann.lecun.com/exdb/publis/pdf/lecun-98.pdf
+
+
+from resnet18 import ResNet18
+import tensorflow as tf
+import numpy as np
+import matplotlib.pyplot as plt
+# Pour les utilisateurs de MacOS  (pour utiliser plt & keras en même temps)
+import os
+#os.environ['KMP_DUPLICATE_LIB_OK']='True'
+
+
+def displayConvFilers(model, layer_name, num_filter=4, filter_size=(3,3), num_channel=0, fig_size=(2,2)):
+    
+    layer_dict = dict([(layer.name, layer) for layer in mnist_model.layers])
+    
+    weight, biais = layer_dict[layer_name].get_weights()
+    print(weight.shape) 
+    plt.figure(figsize=fig_size)
+    for i in range(num_filter):
+        plt.subplot(fig_size[0],fig_size[1],i+1)
+        plt.xticks([])
+        plt.yticks([])
+        plt.grid(False)
+        vis = np.reshape(weight[:,:,num_channel,i],filter_size)
+        plt.imshow(vis, cmap=plt.cm.binary)
+    plt.show()
+
+
+def snake(x):
+    return x + tf.sin(x)**2
+
+
+## Chargement et normalisation des données
+resnet18 = tf.keras.datasets.cifar10
+(train_images, train_labels), (test_images, test_labels) = resnet18.load_data()
+train_images = train_images / 255.0
+test_images = test_images / 255.0
+
+# POUR LES CNN : On rajoute une dimension pour spécifier qu'il s'agit d'imgages en NdG
+train_images = train_images.reshape(50000,32,32,3)
+test_images = test_images.reshape(10000,32,32,3)
+
+
+# One hot encoding
+train_labels = tf.keras.utils.to_categorical(train_labels)
+test_labels = tf.keras.utils.to_categorical(test_labels)
+
+filter_size_conv1 = (3,3)
+
+model = ResNet18(10)
+model.build(input_shape = (None,32,32,3))
+
+
+# expliquer le nombre de paramètre de ce réseau
+print(model.summary())
+
+
+sgd = tf.keras.optimizers.Adam()
+
+model.compile(sgd, loss='categorical_crossentropy', metrics=['accuracy'])
+
+# On visualise avant l'entrainement
+'''
+displayConvFilers(mnist_model, 'conv2d', 
+                    num_filter=6, 
+                    filter_size=filter_size_conv1, 
+                    num_channel=0, 
+                    fig_size=(2,3)
+                )
+'''
+
+
+model.fit(train_images,
+         train_labels,
+         batch_size=64,
+         epochs=4
+         )
+
+## Evaluation du modèle 
+test_loss, test_acc = model.evaluate(test_images, test_labels)
+print('Test accuracy:', test_acc)
+
+
+'''
+displayConvFilers(mnist_model,
+                    'conv2d', 
+                    num_filter=6, 
+                    filter_size=filter_size_conv1, 
+                    num_channel=0, 
+                    fig_size=(2,3)
+                )
+'''
+
+'''
+displayConvFilers(mnist_model, 'conv2d_1', 
+                    num_filter=16, 
+                    filter_size=(5,5), 
+                    num_channel=1, 
+                    fig_size=(4,4)
+                )
+'''