Arrays Tutorial 6 : Using reference Arrays

This page explains how to create reference on existing arrays.

Creating reference to sub-arrays

Any slice of an existing array can be referenced by an other array and modified using this "reference" container.

Example

Output

#include "STKpp.h" using namespace STK; int main(int argc, char** argv) { ArraySquareX a(4); a << 1.,2.,3.,4. , 1.,2.,3.,4. , 1.,1.,1.,1. , 1.,1.,1.,1.; // create a reference ArrayXX b(a.sub(Range(2), Range(3)), true); b = -1.; std::cout << "Modified a=\n" << a << "\n"; CArray<Real, 3, 4> c; c << 1.,2.,3.,4. , 1.,2.,3.,4. , 1.,1.,1.,1.; // create a reference CVector3 d(c.col(1), true); d = -1.; std::cout << "Modified c=\n" << c; return 0; }

Modified a= -1 -1 -1 4 -1 -1 -1 4 1 1 1 1 1 1 1 1 Modified c= 1 -1 3 4 1 -1 3 4 1 -1 1 1

This method allow to get a safe access to some sub-part of a big array that you want to modify.

Creating reference to raw data

It is possible to map a single pointer Type* or a double pointer Type** in respectively CArrays and Array2Ds using the constructors.

Wrapper Constructors	Examples
Wrap the data pointed by q in an Array with rows in the range I and columns in the range J. Array2D<Type>( Type** q, Range const& I, Range const& J);	In this example we create an array of size (10, 5) and wrap it in an Array2. Real** q = new Real*[10]; for (int j=0; j<10; j++) { q[j] = new Real[5];} //wrap q. Note that q will not be freed when a is deleted Array2D<Real> a(q, Range(0,10), Range(0,5)); //
Wrapper constructor. Wrap the data pointed by q in an Array with rows and columns of size m and n. CArray<Type>( Type* q, int m, int n);	In this example we create an array of size (10, 5) and wrap it in an Array2D. Real* q = new Real[10]; for (int j=0; j<10; j++) { q[j] = j;} //wrap q in a fixed size array of size (2,5). // Note that q will not be freed when a is deleted CArray<Real, 2, 5> a(q, 2, 5);