tensorflow 变量

Posted 2020-10-14 哈哈哈

tf.get_variable(): 不受 name_scope 的影响，在未指定共享变量时，重名报错

tf.Variable()    ： 会自动检测有无重名，重名自行处理

with tf.name_scope(‘name_scope_1‘):# name_scope 的作用封装一堆操作，使数据流图有层次感
    var1 = tf.get_variable(name=‘var1‘, shape=[1], dtype=tf.float32)
    var2 = tf.get_variable(name=‘var1‘, shape=[1], dtype=tf.float32)
with tf.Session() as sess:
    sess.run(tf.global_variables_initializer())
    print(var1.name, sess.run(var1))
    print(var2.name, sess.run(var2))

# ValueError: Variable var1 already exists, disallowed. Did you mean 
# to set reuse=True in VarScope? Originally defined at:
# var1 = tf.get_variable(name=‘var1‘, shape=[1], dtype=tf.float32)

当需要共享变量时，使用tf.variable_scope()

with tf.variable_scope(‘variable_scope_y‘) as scope:
    var1 = tf.get_variable(name=‘var1‘, shape=[1], dtype=tf.float32)
    scope.reuse_variables()  # 设置共享变量
    var1_reuse = tf.get_variable(name=‘var1‘)
    var2 = tf.Variable(initial_value=[2.], name=‘var2‘, dtype=tf.float32)
    var2_reuse = tf.Variable(initial_value=[2.], name=‘var2‘, dtype=tf.float32)

with tf.Session() as sess:
    sess.run(tf.global_variables_initializer())
    print(var1.name, sess.run(var1))
    print(var1_reuse.name, sess.run(var1_reuse))
    print(var2.name, sess.run(var2))
    print(var2_reuse.name, sess.run(var2_reuse))
# 输出结果：
# variable_scope_y/var1:0 [-1.59682846]
# variable_scope_y/var1:0 [-1.59682846]   可以看到变量var1_reuse重复使用了var1
# variable_scope_y/var2:0 [ 2.]
# variable_scope_y/var2_1:0 [ 2.]
也可以这样with tf.variable_scope(‘foo‘) as foo_scope:
    v = tf.get_variable(‘v‘, [1])
with tf.variable_scope(‘foo‘, reuse=True):
    v1 = tf.get_variable(‘v‘)
assert v1 == v
或者这样：with tf.variable_scope(‘foo‘) as foo_scope:
    v = tf.get_variable(‘v‘, [1])
with tf.variable_scope(foo_scope, reuse=True):
    v1 = tf.get_variable(‘v‘)
assert v1 == v