tensorflow實戰——tensorflow實現AlexNet
阿新 • • 發佈:2018-12-10
#%% # Copyright 2015 The TensorFlow Authors. All Rights Reserved. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. # ============================================================================== from datetime import datetime import math import time import tensorflow as tf batch_size=32 num_batches=100 #一個用來顯示每一層jiego def print_activations(t): #接受一個tensor作為輸入,顯示其名稱和tensor尺寸 print(t.op.name, ' ', t.get_shape().as_list()) def inference(images): parameters = [] # conv1 #通過這種寫法可以將scope內生成的Variable自動命名為c #onv1/xxx,便於區分不同卷積層之間的元件 with tf.name_scope('conv1') as scope: #使用截斷的正太分佈函式初始化卷積核的引數kernel kernel = tf.Variable(tf.truncated_normal([11, 11, 3, 64], dtype=tf.float32, stddev=1e-1), name='weights') conv = tf.nn.conv2d(images, kernel, [1, 4, 4, 1], padding='SAME') biases = tf.Variable(tf.constant(0.0, shape=[64], dtype=tf.float32), trainable=True, name='biases') #將conv和biases加起來 bias = tf.nn.bias_add(conv, biases) conv1 = tf.nn.relu(bias, name=scope) #列印conv1的結構 print_activations(conv1) parameters += [kernel, biases] # pool1 #4:depth_radius lrn1 = tf.nn.lrn(conv1, 4, bias=1.0, alpha=0.001 / 9.0, beta=0.75, name='lrn1') #第二個引數ksize:池化視窗的大小,取一個四維向量,一般是[1, height, width, 1], #因為我們不想在batch和channels上做池化,所以這兩個維度設為了1 pool1 = tf.nn.max_pool(lrn1, ksize=[1, 3, 3, 1], strides=[1, 2, 2, 1], padding='VALID', name='pool1') print_activations(pool1) # conv2 with tf.name_scope('conv2') as scope: #輸入通道數急死上一層的卷積核數量 kernel = tf.Variable(tf.truncated_normal([5, 5, 64, 192], dtype=tf.float32, stddev=1e-1), name='weights') #卷積的步長全部設為1 conv = tf.nn.conv2d(pool1, kernel, [1, 1, 1, 1], padding='SAME') biases = tf.Variable(tf.constant(0.0, shape=[192], dtype=tf.float32), trainable=True, name='biases') bias = tf.nn.bias_add(conv, biases) conv2 = tf.nn.relu(bias, name=scope) parameters += [kernel, biases] print_activations(conv2) # pool2 lrn2 = tf.nn.lrn(conv2, 4, bias=1.0, alpha=0.001 / 9.0, beta=0.75, name='lrn2') pool2 = tf.nn.max_pool(lrn2, ksize=[1, 3, 3, 1], strides=[1, 2, 2, 1], padding='VALID', name='pool2') print_activations(pool2) # conv3 with tf.name_scope('conv3') as scope: kernel = tf.Variable(tf.truncated_normal([3, 3, 192, 384], dtype=tf.float32, stddev=1e-1), name='weights') conv = tf.nn.conv2d(pool2, kernel, [1, 1, 1, 1], padding='SAME') biases = tf.Variable(tf.constant(0.0, shape=[384], dtype=tf.float32), trainable=True, name='biases') bias = tf.nn.bias_add(conv, biases) conv3 = tf.nn.relu(bias, name=scope) parameters += [kernel, biases] print_activations(conv3) # conv4 with tf.name_scope('conv4') as scope: kernel = tf.Variable(tf.truncated_normal([3, 3, 384, 256], dtype=tf.float32, stddev=1e-1), name='weights') conv = tf.nn.conv2d(conv3, kernel, [1, 1, 1, 1], padding='SAME') biases = tf.Variable(tf.constant(0.0, shape=[256], dtype=tf.float32), trainable=True, name='biases') bias = tf.nn.bias_add(conv, biases) conv4 = tf.nn.relu(bias, name=scope) parameters += [kernel, biases] print_activations(conv4) # conv5 with tf.name_scope('conv5') as scope: kernel = tf.Variable(tf.truncated_normal([3, 3, 256, 256], dtype=tf.float32, stddev=1e-1), name='weights') conv = tf.nn.conv2d(conv4, kernel, [1, 1, 1, 1], padding='SAME') biases = tf.Variable(tf.constant(0.0, shape=[256], dtype=tf.float32), trainable=True, name='biases') bias = tf.nn.bias_add(conv, biases) conv5 = tf.nn.relu(bias, name=scope) parameters += [kernel, biases] print_activations(conv5) # pool5 pool5 = tf.nn.max_pool(conv5, ksize=[1, 3, 3, 1], strides=[1, 2, 2, 1], padding='VALID', name='pool5') print_activations(pool5) return pool5, parameters def time_tensorflow_run(session, target, info_string): # """Run the computation to obtain the target tensor and print timing stats. # # Args: # session: the TensorFlow session to run the computation under. # target: the target Tensor that is passed to the session's run() function. # info_string: a string summarizing this run, to be printed with the stats. # # Returns: # None # """ num_steps_burn_in = 10 total_duration = 0.0 total_duration_squared = 0.0 for i in range(num_batches + num_steps_burn_in): start_time = time.time() _ = session.run(target) duration = time.time() - start_time if i >= num_steps_burn_in: if not i % 10: print ('%s: step %d, duration = %.3f' % (datetime.now(), i - num_steps_burn_in, duration)) total_duration += duration total_duration_squared += duration * duration #平均耗時 mn = total_duration / num_batches vr = total_duration_squared / num_batches - mn * mn #標準差 sd = math.sqrt(vr) print ('%s: %s across %d steps, %.3f +/- %.3f sec / batch' % (datetime.now(), info_string, num_batches, mn, sd)) def run_benchmark(): # """Run the benchmark on AlexNet.""" #定義預設的Graph with tf.Graph().as_default(): # Generate some dummy images. image_size = 224 # Note that our padding definition is slightly different the cuda-convnet. # In order to force the model to start with the same activations sizes, # we add 3 to the image_size and employ VALID padding above. images = tf.Variable(tf.random_normal([batch_size, image_size, image_size, 3], dtype=tf.float32, stddev=1e-1)) # Build a Graph that computes the logits predictions from the # inference model. #構建整個AlexNet網路 pool5, parameters = inference(images) # Build an initialization operation. #初始化所有引數 init = tf.global_variables_initializer() # Start running operations on the Graph. config = tf.ConfigProto() config.gpu_options.allocator_type = 'BFC' sess = tf.Session(config=config) sess.run(init) # Run the forward benchmark. time_tensorflow_run(sess, pool5, "Forward") # Add a simple objective so we can calculate the backward pass. #計算pool5的loss objective = tf.nn.l2_loss(pool5) # Compute the gradient with respect to all the parameters. grad = tf.gradients(objective, parameters) # Run the backward benchmark. time_tensorflow_run(sess, grad, "Forward-backward") run_benchmark()