CODEWITHSUNDEEP
c++vector
user1313080
user1313080

Reputation: 3

Merging vector of vectors

My class is

    class aMatrix {
private:
    std::vector<std::vector<double> > mat;
    unsigned rows;
    unsigned cols; ...}

I want to merge two matrixes using method

aMatrix aMatrix::merge(const aMatrix& ob){
    this->mat.reserve(this->mat.size()+ob.mat.size());
    this->cols+=ob.cols;
    this->mat.insert(this->mat.end(), ob.mat.begin(),ob.mat.end());
    return *this;
}

but it doesnt work. Any ideas how to make it work?

edit: there's no error. it just adds column of ~0 and then values than differ from ob.mat.

edit:

aMatrix mat1(3,3);
mat1(0, 0) = 1;
mat1(0, 1) = 1;
mat1(0, 2) = 1;
mat1(1, 0) = 2;
mat1(1, 1) = 3;
mat1(1, 2) = 5;
mat1(2, 0) = 11;
mat1(2, 1) = 0;
mat1(2, 2) = 5;
aMatrix ones(3,3);
ones(0,0)=1;
ones(1,1)=1;
ones(2,2)=1;

mat1.merge(ones);

the result is:

1, 1, 1, 1.11319e-308, 2, 3, 
2, 3, 5, 1.11318e-308, 11, 0, 
11, 0, 5, 1.11317e-308, 1, 0,

edit: How to make it work in such notation?

// Parameter Constructor
aMatrix::aMatrix(unsigned _rows, unsigned _cols, const double& _initial) {
    mat.resize(_rows);
    for (unsigned i = 0; i < mat.size(); i++) {
        mat[i].resize(_cols, _initial);
    }
    rows = _rows;
    cols = _cols;
}

edit: OK, it works now. right code:

aMatrix& aMatrix::merge(const aMatrix& ob){
this->mat.reserve(this->mat.size()+ob.mat.size());
this->cols+=ob.cols;
for (unsigned i = 0; i < this->mat.size(); i++) {
    this->mat[i].insert(this->mat[i].end(), ob.mat[i].begin(),ob.mat[i].end() );
}
return *this;
}

thanks :)

Upvotes: 0

Views: 83

Answers (1)

Xiaotian Pei
Xiaotian Pei

Reputation: 3260

You should do the merge row by row. What you are doing in your code is adding more rows to the original matrix. What you are intended to do is add more columns to the original matrix.

Upvotes: 1

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