Description of Vector

Vector		Programmers Guide
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Category:containers

Component type:concept

Description

Not to be confused with the std::vector class. The MTL Vector concept is a Container in which every element has a corresponding index. The elements do not have to be sorted by their index, and the indices do not necessarily have to start at 0. Also the indices do not have to form a contiguous range. The iterator type must be a model of IndexedIterator. Vector is not a refinement of RandomAccessContainer (even though Vector defines operator[]) because Vector does not guarantee amortized constant time for that operation (to allow fo sparse vectors). Note also that the invariant a[n] == advance(A.begin(), n) that applies to RandomAccessContainer does not apply to Vector, since the a[i] is defined for Vector to return the element with the ith index. So a[n] == *i if and only if i.index() == n. The indices of the elements in the subrange remain the same. For example, here is a vector written in terms of index-value pairs: x = [ (0,2), (1,5), (2,3), (3,1), (4,9) ] The subrange [1,3) of x can be obtained with y = x(1,3) which results in y = [ (1,5), (2,3) ] The subrange vector is a reference to a particular portion of the original vector. If you wish to have the subrange vector's starting index to be zero just do the following: y = x(1,3).adjust_index(-1); The adjust_index(delta) function does not affect the indexing of the original vector.

Refinement of

Associated types

Concept	Type name	Description
`IndexedIterator`	`X::iterator`
`const IndexedIterator`	`X::const_iterator`
`Tag`	`X::dimension`	Marks this as 1-D
`Tag`	`X::sparsity`	`dense_tag` or `sparse_tag`
`const Vector`	`X::scaled_type`	The vector scaled be a constant
`size_type`	`X::N`	the static size, 0 if dynamic
`const Container`	`X::IndexArray`	An array containing the indices of the elements in the vector.
`Vector`	`X::subrange_type`	The sub-vector type
`const Vector`	`X::const_subrange_type`	The const sub-vector type

Notations

`X`	The type of a model of Vector
`a`	An object of type X
`splits`	A container of integral objects

Definitions

Expression semantics

Description	Expression	Semantics
Element access	`a[n]`
Const element access	`a[n]`
Subrange access	`a(s,f)`
Subrange access	`a[r]`
Number of non-zero elements (actually the number of stored elements)	`a.nnz()`
Adjust the indices of the elements by delta	`x.adjust_index(delta);`

Function specification

Name	Function	Complexity
Element access	`reference operator[](size_type n)`	linear time
Const element access	`const_reference operator[](size_type n)`	linear time
Subrange access	`subrange operator()(size_type start, size_type finish)`	linear time
Subrange access	`subrange operator()(range_type r)`	linear time
Number of non-zero elements (actually the number of stored elements)	`size_type nnz()`	constant time
Adjust the indices of the elements by delta	`self adjust_index(size_type delta)`	constant time

Invariants

a.nnz() <= a.size()

Models

Notes

See also