CODEWITHSUNDEEP
c++multidimensional-array
Mustafa
Mustafa

Reputation: 263

createing a multi dimensional vector of any size

I am trying to create a multi-dimensional histogram using multi-dimentional vectors and I don't know the dimension size ahead of time. Any ideas on how to do this in c++?

Mustafa

Upvotes: 1

Views: 152

Answers (3)

Vibhu Jawa
Vibhu Jawa

Reputation: 88

vector<vector<int>> mutli_dim_vector_name(num_rows, (vector<int>(num_cols, default_value)));

// You can use this format to further nest to the dimensions you want.

Upvotes: 0

James Kanze
James Kanze

Reputation: 153899

Write your own class. For starters, you'll probably want something along the lines of: 

class MultiDimVector
{
    std::vector<int> myDims;
    std::vector<double> myData;
public:
    MultiDimVector( std::vector<int> dims )
        : myDims( dims )
        , myData( std::accumulate( 
            dims.begin(), dims.end(), 1.0, std::multiplies<int>() )
    {
    }
};

For indexing, you'll have to take an std::vector<int> as the index, and calculate it yourself. Basically something along the lines of:

int MultiDimVector::calculateIndex(
    std::vector<int> const& indexes ) const
{
    int results = 0;
    assert( indexes.size() == myDims.size() );
    for ( int i = 0; i != indexes.size(); ++ i ) {
        assert( indexes[i] < myDims[i] );
        results = myDims[i] * results + indexes[i];
    }
    return results;
}

Upvotes: 3

Zlatomir
Zlatomir

Reputation: 7034

You can use std::vector, like:

std::vector<std::vector<yourType> >

(or maybe if you use a framework you can search it's documentation for a better integrated array replacement ;) )

Upvotes: 1

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