How to realize vector append with cuda(or thrust)?

Recently, I need to migrate some computationally intensive code from C++ into cuda C, but these codes are based std::vector and opencv like this:

    // Iterate over each track-detection pair      for (unsigned int i = 0; i < tracks.size(); i++)      {          costMatrix.push_back(vector<double>());            Rect predBbox = tracks[i].predPosition;          for (unsigned int j = 0; j < detections.size(); j++)          {              Rect bbox = detections[j].bbox;                double overlap = computeBoundingBoxOverlap(predBbox, bbox);                // Cost = 1 - overlap              costMatrix[i].push_back(1.0 - overlap);          }      }  

Because push_back() here can only be invoked from host, and I cannot determine the size of vector in advance so malloc memory to pointer is not a good idea. I have tried thrust, but thrust::transform also cannot append data into vector, for which I code like this:

    vector<Student> host_v;      // Init input data        thrust::device_vector<Student> d_s(host_v.begin(), host_v.end());      thrust::device_vector<Student> d_s_1(host_v.begin(), host_v.end());      thrust::transform(d_s.begin(), d_s.end(), d_s_1.end(), [] __device__(Student s) {          ... // some operation          return s;      });      thrust::copy(d_s_1.begin(), d_s_1.end(), host_v.begin()); // change nothing to host_v  

https://stackoverflow.com/questions/65417820/how-to-realize-vector-append-with-cudaor-thrust December 23, 2020 at 09:03AM