#?-*-?coding:?utf-8?-*-

from?keras.optimizers?import?SGD
from?keras.layers?import?Input?merge?ZeroPadding2D
from?keras.layers.core?import?Dense?Dropout?Activation
from?keras.layers.convolutional?import?Convolution2D
from?keras.layers.pooling?import?AveragePooling2D?GlobalAveragePooling2D?MaxPooling2D
from?keras.layers.normalization?import?BatchNormalization
from?keras.models?import?Model
import?keras.backend?as?K

from?sklearn.metrics?import?log_loss

from?custom_layers.scale_layer?import?Scale

from?load_cifar10?import?load_cifar10_data

def?densenet121_model（img_rows?img_cols?color_type=1?nb_dense_block=4?growth_rate=32?nb_filter=64?reduction=0.5?dropout_rate=0.0?weight_decay=1e-4?num_classes=None）:
????‘‘‘
????DenseNet?121?Model?for?Keras

????Model?Schema?is?based?on?
????https://github.com/flyyufelix/DenseNet-Keras

????ImageNet?Pretrained?Weights?
????Theano:?https://drive.google.com/open?id=0Byy2AcGyEVxfMlRYb3YzV210VzQ
????TensorFlow:?https://drive.google.com/open?id=0Byy2AcGyEVxfSTA4SHJVOHNuTXc

????#?Arguments
????????nb_dense_block:?number?of?dense?blocks?to?add?to?end
????????growth_rate:?number?of?filters?to?add?per?dense?block
????????nb_filter:?initial?number?of?filters
????????reduction:?reduction?factor?of?transition?blocks.
????????dropout_rate:?dropout?rate
????????weight_decay:?weight?decay?factor
????????classes:?optional?number?of?classes?to?classify?images
????????weights_path:?path?to?pre-trained?weights
????#?Returns
????????A?Keras?model?instance.
????‘‘‘
????eps?=?1.1e-5

????#?compute?compression?factor
????compression?=?1.0?-?reduction

????#?Handle?Dimension?Ordering?for?different?backends
????global?concat_axis
????if?K.image_dim_ordering（）?==?‘tf‘:
??????concat_axis?=?3
??????img_input?=?Input（shape=（img_rows?img_cols?color_type）?name=‘data‘）
????else:
??????concat_axis?=?1
??????img_input?=?Input（shape=（color_type?img_rows?img_cols）?name=‘data‘）

????#?From?architecture?for?ImageNet?（Table?1?in?the?paper）
????nb_filter?=?64
????nb_layers?=?[6122416]?#?For?DenseNet-121

????#?Initial?convolution
????x?=?ZeroPadding2D（（3?3）?name=‘conv1_zeropadding‘）（img_input）
????x?=?Convolution2D（nb_filter?7?7?subsample=（2?2）?name=‘conv1‘?bias=False）（x）
????x?=?BatchNormalization（epsilon=eps?axis=concat_axis?name=‘conv1_bn‘）（x）
????x?=?Scale（axis=concat_axis?name=‘conv1_scale‘）（x）
????x?=?Activation（‘relu‘?name=‘relu1‘）（x）
????x?=?ZeroPadding2D（（1?1）?name=‘pool1_zeropadding‘）（x）
????x?=?MaxPooling2D（（3?3）?strides=（2?2）?name=‘pool1‘）（x）

????#?Add?dense?blocks
????for?block_idx?in?range（nb_dense_block?-?1）:
????????stage?=?block_idx+2
????????x?nb_filter?=?dense_block（x?stage?nb_layers[block_idx]?nb_filter?growth_rate?dropout_rate=dropout_rate?weight_decay=weight_decay）

????????#?Add?transition_block
????????x?=?transition_block（x?stage?nb_filter?compression=compression?dropout_rate=dropout_rate?weight_decay=weight_decay）
????????nb_filter?=?int（nb_filter?*?compression）

????fi