Tensorflow C++ Placeholder initialization

3
votes

I was trying to perform image captioning with tensorflow on cpp. I was following the direction on How to import an saved Tensorflow model train using tf.estimator and predict on input data and tried

int main(int argc, char**) {
....
    auto x = tf::Tensor(tf::DT_UINT8, tf::TensorShape({height, width, channel}));
    auto matrix = x.matrix<char>();
....
}

When I compile the program, the code 

> In file included from /usr/local/include/tensorflow/core/framework/tensor.h:26:0,
                 from /usr/local/include/tensorflow/core/public/session.h:23,
                 from /usr/local/include/tensorflow/cc/saved_model/loader.h:26,
                 from server.cpp:22:
/usr/local/include/tensorflow/core/framework/types.h: In instantiation of ‘struct tensorflow::DataTypeToEnum<char>’:
/usr/local/include/tensorflow/core/framework/tensor.h:530:46:   required from ‘typename tensorflow::TTypes<T, NDIMS>::Tensor tensorflow::Tensor::tensor() [with T = char; long unsigned int NDIMS = 2ul; typename tensorflow::TTypes<T, NDIMS>::Tensor = Eigen::TensorMap<Eigen::Tensor<char, 2, 1, long int>, 16, Eigen::MakePointer>]’
/usr/local/include/tensorflow/core/framework/tensor.h:240:25:   required from ‘typename tensorflow::TTypes<T>::Matrix tensorflow::Tensor::matrix() [with T = char; typename tensorflow::TTypes<T>::Matrix = Eigen::TensorMap<Eigen::Tensor<char, 2, 1, long int>, 16, Eigen::MakePointer>]’
server.cpp:121:34:   required from here
/usr/local/include/tensorflow/core/framework/types.h:138:3: error: static assertion failed: Specified Data Type not supported
   static_assert(IsValidDataType<T>::value, "Specified Data Type not supported");In file included from /usr/local/include/tensorflow/core/public/session.h:23:0,
             from /usr/local/include/tensorflow/cc/saved_model/loader.h:26,
             from server.cpp:22:
/usr/local/include/tensorflow/core/framework/tensor.h: In instantiation of ‘typename tensorflow::TTypes<T, NDIMS>::Tensor tensorflow::Tensor::tensor() [with T = char; long unsigned int NDIMS = 2ul; typename tensorflow::TTypes<T, NDIMS>::Tensor = Eigen::TensorMap<Eigen::Tensor<char, 2, 1, long int>, 16, Eigen::MakePointer>]’:
/usr/local/include/tensorflow/core/framework/tensor.h:240:25:   required from ‘typename tensorflow::TTypes<T>::Matrix tensorflow::Tensor::matrix() [with T = char; typename tensorflow::TTypes<T>::Matrix = Eigen::TensorMap<Eigen::Tensor<char, 2, 1, long int>, 16, Eigen::MakePointer>]’
server.cpp:121:34:   required from here
/usr/local/include/tensorflow/core/framework/tensor.h:530:46: error: ‘v’ is not a member of ‘tensorflow::DataTypeToEnum<char>’
   CheckTypeAndIsAligned(DataTypeToEnum<T>::v());

Did anybody came across the same problem?

2
c++tensorflow

2 Answers

2
votes

Found a solution. It seems like two issues were present. (1) DT_UINT8 is uchar in c++ (2) use tensor instead of matrix

I changed the code to 

auto x = tf::Tensor(tf::DT_UINT8, tf::TensorShape(
                        {height, width,3}));
auto matrix = x.tensor<uchar, 3>();

and worked. Got the idea from https://github.com/tensorflow/tensorflow/issues/19909

2
votes

Even though you declare your TensorShape with an initialization list, you should still specify the number of dimensions of your matrix, as it cannot be deduced at compilation time in C++.

auto x = tf::Tensor(tf::DT_UINT8, tf::TensorShape({height, width, channel}));
auto matrix = x.matrix<char, 3>();