# Sparse Storage

## Default Standard Map

#### Description

The templated class `map_std<I, T, ALLOC>` provides a wrapper for the standard library associative container `std::map`. The wrapper has one simple purpose. It allows the definition of a default template parameter (for the adapted array) when declaring the sparse container types.

#### Example

    #include <boost/numeric/ublas/storage_sparse.hpp>

    int main () {
        using namespace boost::numeric::ublas;
        map_std<int, double> a (3);
        for (unsigned i = 0; i < a.size (); ++ i) {
            a [i] = i;
            std::cout << a [i] << std::endl;
        }
    }

#### Definition

Defined in the header storage_sparse.hpp.

#### Template parameters

Parameter | Description | Default
--- | --- | ---
`I` | The type of index stored in the array. |
`T` | The type of object stored in the array. |
`ALLOC` | An STL Allocator | std::allocator

#### Model of

Reversible Container.

#### Type requirements

None, except for those imposed by the requirements of Reversible Container.

#### Public base classes

std::map

## Map Array

#### Description

The templated class `map_array<I, T, ALLOC>` implements a `std::map` like associative container as a sorted array. It therefore some of the Associative Container interface without having the same semantics as an std::map.

At any time the `map_array` has a capacity up to which new element can be inserted. If `insert` would cause the size of the `map_array` to exceeds its capactity then it is reallocated. Iterators and reference are invalidated. The capacity can be directly control using the `reserve` member function.

#### Example

    #include <boost/numeric/ublas/storage_sparse.hpp>

    int main () {
        using namespace boost::numeric::ublas;
        map_array<int, double> a (3);
        for (unsigned i = 0; i < a.size (); ++ i) {
            a [i] = i;
            std::cout << a [i] << std::endl;
        }
    }

#### Definition

Defined in the header storage_sparse.hpp.

#### Template parameters

Parameter | Description | Default
--- | --- | ---
`I` | The type of index stored in the array. |
`T` | The type of object stored in the array. |
`ALLOC` | An STL Allocator | std::allocator

#### Model of

Reversible Container.

#### Type requirements

None, except for those imposed by the requirements of Reversible Container.

#### Public base classes

None.

#### Members

Member | Description
--- | ---
`map_array (ALLOC &a = ALLOC())` | Allocates a `map_array` that holds at most zero elements.
`map_array (const map_array &c)` | The copy constructor.
`~map_array ()` | Deallocates the `map_array` itself.
`void reserve (size_type capacity)` | Changes the`map_array` capacity. It can hold at most`capacity` elements without reallocation. The capacity can be reduced such that `capacity >= size()`. The content of the`map_array` is preserved.
`size_type size () const` | Returns the size of the `map_array`.
`size_type size () const` | Returns the capacity of the `map_array`.
`data_reference operator [] (index_type i)` | Returns a reference of the element that is associated with a particular index. If the `map_array` does not already contain such an element, `operator[]` inserts the default `T ()`.
`map_array &operator = (const map_array &a)` | The assignment operator.
`map_array &assign_temporary (map_array &a)` | Assigns a temporary. May change the array `a`.
`void swap (map_array &a)` | Swaps the contents of the arrays.
`pointer insert (pointer it, const value_type &p)` | Inserts `p` into the array, using `it` as a hint to where it will be inserted.
`void erase (pointer it)` | Erases the value at `it`.
`void clear ()` | Clears the array.
`const_pointer find (index_type i) const` | Finds an element whose index is `i`.
`pointer find (index_type i)` | Finds an element whose index is `i`.
`const_pointer lower_bound (index_type i) const` | Finds the first element whose index is not less than `i` .
`pointer lower_bound (index_type i)` | Finds the first element whose index is not less than `i` .
`const_pointer upper_bound (index_type i) const` | Finds the first element whose index is greater than `i` .
`pointer upper_bound (index_type i)` | Finds the first element whose index is greater than `i` .
`const_iterator begin () const` | Returns a `const_iterator` pointing to the beginning of the `map_array`.
`const_iterator end () const` | Returns a `const_iterator` pointing to the end of the `map_array`.
`iterator begin ()` | Returns a `iterator` pointing to the beginning of the `map_array`.
`iterator end ()` | Returns a `iterator` pointing to the end of the `map_array`.
`const_reverse_iterator rbegin () const` | Returns a `const_reverse_iterator` pointing to the beginning of the reversed `map_array`.
`const_reverse_iterator rend () const` | Returns a `const_reverse_iterator` pointing to the end of the reversed `map_array`.
`reverse_iterator rbegin ()` | Returns a `reverse_iterator` pointing to the beginning of the reversed `map_array`.
`reverse_iterator rend ()` | Returns a `reverse_iterator` pointing to the end of the reversed `map_array`.

Copyright (©) 2000-2002 Joerg Walter, Mathias Koch
Permission to copy, use, modify, sell and distribute this document is granted provided this copyright notice appears in all copies. This document is provided ``as is'' without express or implied warranty, and with no claim as to its suitability for any purpose.

Last revised: 1/15/2003