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118 lines
6.8 KiB
ReStructuredText
118 lines
6.8 KiB
ReStructuredText
.. highlight:: c
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Value classes and their constructors
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==============================================================================
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* The value classes array, matrix and vector have very similar constructors.
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We will therefore describe only for the array, and mention the difference for matrix and vector below.
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* As mentioned earlier, they are *values*,
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so all these constructors make a **copy** of the data, except of course the move constructor.
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Constructors of array
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---------------------------
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========================================== ===========================================================================================
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Constructors of array Comments
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========================================== ===========================================================================================
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array() Empty array of size 0
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------------------------------------------ -------------------------------------------------------------------------------------------
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array(size_t, ...., size_t) From the lengths of the array dimensions, with Rank arguments (checked at compile time).
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Does **NOT** initialize the array elements to 0 ! (see compile time option)
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------------------------------------------ -------------------------------------------------------------------------------------------
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array(const array &) Copy construction
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------------------------------------------ -------------------------------------------------------------------------------------------
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array(array &&) Move construction
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------------------------------------------ -------------------------------------------------------------------------------------------
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array(const T & X) Type T models the :ref:`HasImmutableArrayInterface` concept.
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- X must have the appropriate domain (checked at compile time).
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- Constructs a new array of domain X.domain() and fills it with evaluation of X.
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------------------------------------------ -------------------------------------------------------------------------------------------
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array(shape_t const &) New array with the corresponding shape (as returned by the function shape. See example
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in section XXX).
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------------------------------------------ -------------------------------------------------------------------------------------------
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array(PyObject * X) Construct a new array from the Python object X.
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NB : X is a borrowed reference, array does affect its counting reference.
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- it takes a **copy** of the data of X (or of numpy(X)) into C++.
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- X is first transformed into a numpy by the python numpy lib itself
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(as if you call numpy.array(X)) if X is not a numpy array or an array of the wrong type
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(e.g. you construct an array<double,2> from a numpy of int....), and
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copied into the array.
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========================================== ===========================================================================================
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.. warning::
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The constructor from the dimensions does **NOT** initialize the array to 0
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(because it may not be optimal).
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If needed, do it explicitely by (a if the array) `a()=0`;, see section ?.
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Constructors of matrix
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---------------------------
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* matrix have similar constructors
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========================================== ===========================================================================================
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Constructors of matrix Comments
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========================================== ===========================================================================================
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matrix() empty matrix of size 0
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matrix(size_t, size_t) from the dimensions. Does NOT initialize the elements of matrix to 0 !
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matrix(const matrix &) copy construction
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matrix(matrix &&) move construction
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matrix (PyObject * X) Construct a new matrix from the Python object X.
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matrix(const T & X) Type T models the :ref:`HasImmutableArrayInterface` concept. Same as array.
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========================================== ===========================================================================================
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Constructors of vector
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---------------------------
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========================================== ===========================================================================================
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Constructors of vector Comments
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========================================== ===========================================================================================
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vector() empty vector of size 0
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vector(size_t) from the dimensions. Does NOT initialize the elements of vector to 0 !
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vector(const vector &) copy construction
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vector(vector &&) move construction
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vector (PyObject * X) Construct a new vector from the Python object X.
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vector(const T & X) Type T models the :ref:`HasImmutableArrayInterface` concept. Same as array.
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========================================== ===========================================================================================
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Examples
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------------
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.. compileblock::
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#include <triqs/arrays.hpp>
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using triqs::arrays::array; using triqs::arrays::matrix;
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using triqs::arrays::vector; using triqs::arrays::permutation;
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int main(){
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// A 3d array of long, C ordering, no option
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array<long, 3> A3(1,2,3);
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// A 2d array of double, C ordering, with explicit Bound Checking
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array<double, 2> B(1,2);
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// a matrix of long
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matrix<long> M(2,2);
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// a vector of double
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vector<double> V(10);
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// arrays with custom TraversalOrder
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// C-style
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array<long, 3, 0, permutation(2,1,0)> A0(2,3,4);
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array<long, 3, 0> A0b; // same type but empty
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// Fortran-style
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array<long, 3, TRAVERSAL_ORDER_FORTRAN> A4 (2,3,4);
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array<long, 3, 0, permutation(0,1,2)> A1b; //same type but empty
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// custom : (i,j,k) : index j is fastest, then k, then i
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array<long, 3, 0, permutation(1,0,2)> A2(2,3,4);
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}
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