matrix.cpp:307: error: (-215) s >= 0 about dbow3 HOT 3 OPEN

hi,@liudongdong1
Have you worked out any approach to solve the problem? I also meet that when I load a database file.
I get the error at this statement: DBoW3::Database db( database_dir ); the error is as follows:
OpenCV Error: Assertion failed (s >= 0) in setSize, file /home/robot/opencv-3.3.0/modules/core/src/matrix.cpp, line 310 terminate called after throwing an instance of 'cv::Exception'
what(): /home/robot/opencv-3.3.0/modules/core/src/matrix.cpp:310: error: (-215) s >= 0 in function setSize

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i found the answer which already solved by other in issues,and change it,
void DescManip::fromString(cv::Mat &a, const std::string &s)
{
string ss_aux;
stringstream ss(s);
ss>>ss_aux;
if(ss_aux.find("dbw3")==std::string::npos){
int val;
vector data;data.reserve(100);
while( ss>>val) data.push_back(val);
a.create(1,data.size(),CV_8UC1);
memcpy(a.ptr(0),&data[0],data.size());
}
else{
int type,cols;
ss >>type>>cols;
a.create(1, cols, type);
if(type==CV_8UC1){
unsigned char *p = a.ptr();
int n;
for(int i = 0; i < a.cols; ++i, ++p)
if ( ss >> n) *p = (unsigned char)n;
}
else{
float *p = a.ptr();
for(int i = 0; i < a.cols; ++i, ++p)
if ( !(ss >> *p))cerr<<"Error reading. Unexpected EOF. DescManip::fromString"<<endl;
}

}

}
it does work

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Thank you very much,it really works after change,but there are two small mistake in the code you given,

vector data;data.reserve(100);

float *p = a.ptr();

I corrected it and it worked.thank you!

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