如何在Tensorflow中可视化cnn中的权重(变量)?
python
tensorflow
6
0

训练了cnn模型后,我想可视化权重或打印出权重,该怎么办?训练后我什至无法打印出变量。谢谢!

参考资料:
Stack Overflow
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要可视化权重,可以使用tf.image_summary() op将卷积过滤器(或过滤器的一部分)转换为摘要原型,使用tf.train.SummaryWriter将其写入日志,并可视化日志使用TensorBoard

假设您有以下(简化)程序:

filter = tf.Variable(tf.truncated_normal([8, 8, 3]))
images = tf.placeholder(tf.float32, shape=[None, 28, 28])

conv = tf.nn.conv2d(images, filter, strides=[1, 1, 1, 1], padding="SAME")

# More ops...
loss = ...
optimizer = tf.GradientDescentOptimizer(0.01)
train_op = optimizer.minimize(loss)

filter_summary = tf.image_summary(filter)

sess = tf.Session()
summary_writer = tf.train.SummaryWriter('/tmp/logs', sess.graph_def)
for i in range(10000):
  sess.run(train_op)
  if i % 10 == 0:
    # Log a summary every 10 steps.
    summary_writer.add_summary(filter_summary, i)

完成此操作后,您可以启动TensorBoard以可视化/tmp/logs ,并且您将能够看到过滤器的可视化。

请注意,此技巧将深度为3的滤镜可视化为RGB图像(以匹配输入图像的通道)。如果您有更深的滤镜,或者将它们解释为颜色通道没有意义,则可以使用tf.split() op在深度维度上拆分滤镜,并为每个深度生成一个图像摘要。

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就像@mrry所说的,您可以使用tf.image_summary 。例如,对于cifar10_train.py ,您可以将此代码放在def train()下的某个位置。注意如何在作用域'conv1'下访问var

# Visualize conv1 features
with tf.variable_scope('conv1') as scope_conv:
  weights = tf.get_variable('weights')

  # scale weights to [0 255] and convert to uint8 (maybe change scaling?)
  x_min = tf.reduce_min(weights)
  x_max = tf.reduce_max(weights)
  weights_0_to_1 = (weights - x_min) / (x_max - x_min)
  weights_0_to_255_uint8 = tf.image.convert_image_dtype (weights_0_to_1, dtype=tf.uint8)

  # to tf.image_summary format [batch_size, height, width, channels]
  weights_transposed = tf.transpose (weights_0_to_255_uint8, [3, 0, 1, 2])

  # this will display random 3 filters from the 64 in conv1
  tf.image_summary('conv1/filters', weights_transposed, max_images=3)

如果要在一个漂亮的网格中可视化所有conv1过滤器,则必须自己将它们组织到一个网格中。我今天做了,所以现在我想分享将conv1可视化为网格要点

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您可以通过以下方式将值提取为numpy数组:

with tf.variable_scope('conv1', reuse=True) as scope_conv:
    W_conv1 = tf.get_variable('weights', shape=[5, 5, 1, 32])
    weights = W_conv1.eval()
    with open("conv1.weights.npz", "w") as outfile:
        np.save(outfile, weights)

请注意,您必须调整范围(在我的情况下为'conv1' )和变量名称(在我的情况下为'weights' )。

然后归结为可视化numpy数组。如何可视化numpy数组的一个示例是

#!/usr/bin/env python

"""Visualize numpy arrays."""

import numpy as np
import scipy.misc

arr = np.load('conv1.weights.npb')

# Get each 5x5 filter from the 5x5x1x32 array
for filter_ in range(arr.shape[3]):
    # Get the 5x5x1 filter:
    extracted_filter = arr[:, :, :, filter_]

    # Get rid of the last dimension (hence get 5x5):
    extracted_filter = np.squeeze(extracted_filter)

    # display the filter (might be very small - you can resize the window)
    scipy.misc.imshow(extracted_filter)
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