zoukankan      html  css  js  c++  java
  • tensorflow函数解析:Session.run和Tensor.eval的区别

    tensorflow函数解析:Session.run和Tensor.eval

    翻译 2017年04月20日 15:05:50

    原问题链接:

    http://stackoverflow.com/questions/33610685/in-tensorflow-what-is-the-difference-between-session-run-and-tensor-eval

    译:

    问题:

    tensorflow有两种方式:Session.run和 Tensor.eval,这两者的区别在哪?

    答:

    如果你有一个Tensor t,在使用t.eval()时,等价于:tf.get_default_session().run(t).

    举例:

    t = tf.constant(42.0)
    sess = tf.Session()
    with sess.as_default():   # or `with sess:` to close on exit
        assert sess is tf.get_default_session()
        assert t.eval() == sess.run(t)

    这其中最主要的区别就在于你可以使用sess.run()在同一步获取多个tensor中的值,

    例如:

    t = tf.constant(42.0)
    u = tf.constant(37.0)
    tu = tf.mul(t, u)
    ut = tf.mul(u, t)
    with sess.as_default():
       tu.eval()  # runs one step
       ut.eval()  # runs one step
       sess.run([tu, ut])  # evaluates both tensors in a single step

    注意到:每次使用 eval 和 run时,都会执行整个计算图,为了获取计算的结果,将它分配给tf.Variable,然后获取。

    原文如下:

    Question:

    TensorFlow has two ways to evaluate part of graph: Session.run on a list of variables and Tensor.eval. Is there a difference between these two?

    Answer:

    If you have a Tensor t, calling t.eval() is equivalent to calling tf.get_default_session().run(t).

    You can make a session the default as follows:

    t = tf.constant(42.0)
    sess = tf.Session()
    with sess.as_default():   # or `with sess:` to close on exit
        assert sess is tf.get_default_session()
        assert t.eval() == sess.run(t)

    The most important difference is that you can use sess.run() to fetch the values of many tensors in the same step:

    t = tf.constant(42.0)
    u = tf.constant(37.0)
    tu = tf.mul(t, u)
    ut = tf.mul(u, t)
    with sess.as_default():
       tu.eval()  # runs one step
       ut.eval()  # runs one step
       sess.run([tu, ut])  # evaluates both tensors in a single step

    Note that each call to eval and run will execute the whole graph from scratch. To cache the result of a computation, assign it to a tf.Variable.

  • 相关阅读:
    App提交Appstore审核流程【转】
    程序员必须软件
    Linux的cron和crontab
    Git操作基本命令
    Python编码问题整理【转】
    Python读取ini配置文件
    RF+Jenkins构建持续集成
    RF接口测试本地环境部署
    Python建立SSH连接与使用方法
    永久修改python默认的字符编码为utf-8
  • 原文地址:https://www.cnblogs.com/adong7639/p/8602378.html
Copyright © 2011-2022 走看看