Getting Blob data in caffe

Question

I am trying to plot layer out of caffe as follow.

    int ncols = (int)(sqrt (blob.channels()));
    int nrows;
    if(blob.channels()%ncols!=0){
        nrows = ncols+1;
    }

    int Rows = nrows*blob.height();
    int Cols = ncols*blob.width();
    cv::Mat image = cv::Mat::zeros(Rows+nrows, Cols+ncols, CV_32FC1);
    ///////Plotting output of individual layer
    if(blob.height()>1 && blob.width()>1){
            cv::Size ss(blob.width(), blob.height());
            Dtype* data = blob.mutable_cpu_data();
            int r=0; int c=0;
            for(int k=0; k < blob.channels(); k++)
            {
              cv::Mat channel(ss, CV_32FC1, data);

              channel.copyTo(image(cv::Rect(c*blob.width()+1, r*blob.height()+1,  blob.width(), blob.height())));
              c++;
              if(c>0 &&c%ncols==0){
                  r++;
                  c=0;
              }

              channel.release();
              data += ss.area();
            }
    }

For that I have error as

CXX src/caffe/net.cpp
src/caffe/net.cpp: In instantiation of ‘void caffe::Net<Dtype>::ForwardDebugInfo(int) [with Dtype = float]’:
src/caffe/net.cpp:1040:1:   required from here
src/caffe/net.cpp:632:49: error: passing ‘const caffe::Blob<float>’ as ‘this’ argument discards qualifiers [-fpermissive]
             Dtype* data = blob.mutable_cpu_data();
                                                 ^
In file included from ./include/caffe/layer.hpp:8:0,
                 from src/caffe/net.cpp:11:
./include/caffe/blob.hpp:225:10: note:   in call to ‘Dtype* caffe::Blob<Dtype>::mutable_cpu_data() [with Dtype = float]’
   Dtype* mutable_cpu_data();
          ^
src/caffe/net.cpp: In instantiation of ‘void caffe::Net<Dtype>::ForwardDebugInfo(int) [with Dtype = double]’:
src/caffe/net.cpp:1040:1:   required from here
src/caffe/net.cpp:632:49: error: passing ‘const caffe::Blob<double>’ as ‘this’ argument discards qualifiers [-fpermissive]
             Dtype* data = blob.mutable_cpu_data();
                                                 ^
In file included from ./include/caffe/layer.hpp:8:0,
                 from src/caffe/net.cpp:11:
./include/caffe/blob.hpp:225:10: note:   in call to ‘Dtype* caffe::Blob<Dtype>::mutable_cpu_data() [with Dtype = double]’
   Dtype* mutable_cpu_data();
          ^
Makefile:575: recipe for target '.build_debug/src/caffe/net.o' failed
make: *** [.build_debug/src/caffe/net.o] Error 1

What does that error means? Earlier version of caffe, it was fine. I did it before. Now what could be the error?

Swift - Friday Pie · Accepted Answer · 2018-01-12 05:52:31Z

2

That error translates as "You pass a const object as this argument to a non-const method mutable_cpu_data"

const Dtype* cpu_data() const;
Dtype* mutable_cpu_data();

"Passing an object as this argument" suggests use of operators . or -> to access object's method and use of operator().

If you do that, you potentially can change const object, so it's an error, unless permissive mode engaged.

answered Jan 12, 2018 at 5:52

Swift - Friday Pie

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2 Comments

batuman Over a year ago

So the error happened at this line Dtype* data = blob.mutable_cpu_data(); how can I fix it?

batuman Over a year ago

Thanks I removed const from this line (Blob<Dtype>& blob = *top_vecs_[layer_id][top_id];) and it is ok.

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