在C ++中为Tensorflow模型定义feed_dict [英] Define a feed_dict in c++ for Tensorflow models

问题描述

这个问题与此相关：
从Python导出Tensorflow图以用于C ++

我正在尝试将Tensorflow模型从Python导出到C ++。问题是，我的神经网络从占位符开始以接收输入，这需要feed_dict。我找不到任何c ++ API为模型提供feed_dict。我该怎么办？

I'm trying to export a Tensorflow model from Python to C++. The problem is, my neural net starts with a placeholder to receive input, which requires a feed_dict. I cannot find any c++ API to supply a feed_dict for my model. What can I do?

如果没有提供feed_dicts的API，我应该如何更改我的模型，以便可以在没有占位符的情况下对它进行训练和导出以用于c ++？

If there's no API for supplying feed_dicts, how should I change my model so that it can be trained and exported for c++ purposes without placeholders?

推荐答案

tensorflow :: Session :: Run（） 方法在C ++中与Python tf.Session.run（） 方法，它支持使用 inputs 参数输入张量。就像C ++和Python中的许多东西一样，它使用起来有点棘手（在这种情况下，文档看起来有点穷...）。

The tensorflow::Session::Run() method is the C++ equivalent of the Python tf.Session.run() method, and it supports feeding tensors using the inputs argument. Like so many things in C++ versus Python, it's just a little more tricky to use (and in this case it looks like the documentation is a bit poorer...).

输入参数的类型为 const std :: vector< std :: pair< string，Tensor>& 。让我们来分解一下：

The inputs argument has type const std::vector<std::pair<string, Tensor>>&. Let's break this down:

• 每个输入元素对应一个您想要在 Run（）调用中提供的单个张量（例如占位符）。元素的类型为 std :: pair< string，Tensor> 。

• Each element of inputs corresponds to a single tensor (such as a placeholder) that you want to feed in the Run() call. An element has type std::pair<string, Tensor>.

std :: pair< string，Tensor> 是要馈送的图中张量的名称。例如，假设在Python中您拥有：

The first element of the std::pair<string, Tensor> is the name of the tensor in the graph that you want to feed. For example, let's say in Python you had:

p = tf.placeholder(..., name="placeholder")
# ...
sess.run(..., feed_dict={p: ...})

...然后在C ++中，该对的第一个元素将是 p.name 的值，在这种情况下为占位符：0

...then in C++ the first element of the pair would be the value of p.name, which in this case would be "placeholder:0"

std :: pair<的第二个元素; string，Tensor> 是您想要提供的值，作为 tensorflow :: Tensor 对象。您必须使用C ++自己构建它，定义一个Numpy数组或Python对象要复杂一些，但这是一个如何指定2 x 2矩阵的示例：

The second element of the std::pair<string, Tensor> is the value that you want to feed, as a tensorflow::Tensor object. You have to build this yourself in C++, and it's a bit more complicated that defining a Numpy array or a Python object, but here's an example of how to specify a 2 x 2 matrix:

using tensorflow::Tensor;
using tensorflow::TensorShape;

Tensor t(DT_FLOAT, TensorShape({2, 2}));
auto t_matrix = t.matrix<float>();
t_matrix(0, 0) = 1.0;
t_matrix(0, 1) = 0.0;
t_matrix(1, 0) = 0.0;
t_matrix(1, 1) = 1.0;

...然后可以通过 t 作为配对中的第二个元素。

...and you can then pass t as the second element of the pair.

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