[英]How do I set the value of an input tensor in c++?
I'm trying to run a sample through a pre trained model on ios. 我正试图通过ios上经过预先训练的模型运行样本。 session->Run() takes as input a tensor to my understanding. session-> Run()将张量作为输入作为我的理解。 I have initialized a tensor, but how do i set it's value? 我已经初始化了张量,但我如何设置它的值? I don't have much experience using C++. 我没有太多使用C ++的经验。
I have successfully created a test model that accepts 3 dimensional tensor of shape {1, 1, 10}. 我已成功创建了一个接受3维张量形状{1,1,10}的测试模型。
I pulled the following line of code from Tensorflow's simple example to create the input tensor. 我从Tensorflow的简单示例中提取了以下代码行来创建输入张量。
https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/ios_examples/simple/RunModelViewController.mm#L189 https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/ios_examples/simple/RunModelViewController.mm#L189
tensorflow::Tensor input_tensor(tensorflow::DT_FLOAT, tensorflow::TensorShape({1,1,10}));
From here, I cannot figure out how I would set the data of input_tensor. 从这里,我无法弄清楚如何设置input_tensor的数据。 I would like to set the tensor to something like {{{.0, .1, .2, .3, .4, .5, .6, .7, .8, .9}}} 我想将张量设置为类似{{{。0,.1,.2,.3,.4,.5,.6,.7,.8,.9}}}的内容。
I had a similar problem and was trying to set the tensor input values in C++ for a model trained in Python. 我有一个类似的问题,并试图在C ++中为使用Python训练的模型设置张量输入值。 The model is a simple NN with one hidden layer to learn to calculate the XOR operation. 该模型是一个简单的NN,具有一个隐藏层,用于学习计算XOR运算。
I first created an output graph file with both the graph structure and the model parameters by following steps 1-4 of this nice post: https://medium.com/@hamedmp/exporting-trained-tensorflow-models-to-c-the-right-way-cf24b609d183#.j4l51ptvb . 我首先按照这个好帖子的步骤1-4创建了一个包含图形结构和模型参数的输出图形文件: https : //medium.com/@hamedmp/exporting-trained-tensorflow-models-to-c- the-right-way-cf24b609d183#.j4l51ptvb 。
Then in C++ (the TensorFlow iOS simple example), I used the following code: 然后在C ++(TensorFlow iOS简单示例)中,我使用了以下代码:
tensorflow::Tensor input_tensor(tensorflow::DT_FLOAT, tensorflow::TensorShape({4,2}));
// input_tensor_mapped is an interface to the data of a tensor and used to copy data into the tensor
auto input_tensor_mapped = input_tensor.tensor<float, 2>();
// set the (4,2) possible input values for XOR
input_tensor_mapped(0, 0) = 0.0;
input_tensor_mapped(0, 1) = 0.0;
input_tensor_mapped(1, 0) = 0.0;
input_tensor_mapped(1, 1) = 1.0;
input_tensor_mapped(2, 0) = 1.0;
input_tensor_mapped(2, 1) = 0.0;
input_tensor_mapped(3, 0) = 1.0;
input_tensor_mapped(3, 1) = 1.0;
tensorflow::Status run_status = session->Run({{input_layer, input_tensor}},
{output_layer}, {}, &outputs);
After this, GetTopN(output->flat<float>(), kNumResults, kThreshold, &top_results);
在此之后, GetTopN(output->flat<float>(), kNumResults, kThreshold, &top_results);
returns the same 4 values (0.94433498, 0.94425952, 0.06565627, 0.05823805), as in my Python test code for XOR after the model is trained, in top_results. 返回相同的4个值(0.94433498,0.94425952,0.06565627,0.05823805),就像我在训练模型后的XOR测试代码中一样,在top_results中。
So if your tensor's shape is {1,1,10}, you can set the values as follows: 因此,如果张量的形状为{1,1,10},则可以按如下方式设置值:
auto input_tensor_mapped = input_tensor.tensor<float, 3>();
input_tensor_mapped(0, 0, 0) = 0.0;
input_tensor_mapped(0, 0, 1) = 0.1;
....
input_tensor_mapped(0, 0, 9) = 0.9;
Credit: the answer at How do I pass an OpenCV Mat into a C++ Tensorflow graph? Credit: 如何将OpenCV Mat传递给C ++ Tensorflow图表? is very helpful. 非常有帮助。
If you want to directly set the value of a tensor you can use few utilities functions provided by the Tensor interface. 如果要直接设置张量的值,可以使用Tensor接口提供的少量实用程序功能。 For the most common linear access you can use flat<T>
. 对于最常见的线性访问,您可以使用flat<T>
。
From tensor_test 来自tensor_test
void ExpectClose(const Tensor& x, const Tensor& y, double atol, double rtol) {
auto Tx = x.flat<T>();
auto Ty = y.flat<T>();
for (int i = 0; i < Tx.size(); ++i) {
if (!IsClose(Tx(i), Ty(i), atol, rtol)) {
LOG(ERROR) << "x = " << x.DebugString();
LOG(ERROR) << "y = " << y.DebugString();
LOG(ERROR) << "atol = " << atol << " rtol = " << rtol
<< " tol = " << atol + rtol * std::fabs(Tx(i));
EXPECT_TRUE(false) << i << "-th element is not close " << Tx(i) << " vs. "
<< Ty(i);
}
}
}
to create a tensor you can use one of the constructors 要创建张量,您可以使用其中一个构造函数
Tensor(DT_FLOAT, new TensorShape(..))
If you want to set the value of a tensor or a placeholder at run time you need to pass it through the Run()
interface: 如果要在运行时设置张量或占位符的值,则需要通过Run()
接口传递它:
Status run_status = session->Run({{input_layer, resized_tensor}},
{output_layer}, {}, &outputs);
if (!run_status.ok()) {
LOG(ERROR) << "Running model failed: " << run_status;
return -1;
}
If you want to have a predefine value of a tensor you can use the Const constructor 如果要使用张量的预定义值,可以使用Const构造函数
tensorflow::ops::Const({input_height, input_width})
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