You are looking at historical revision 4732 of this page. It may differ significantly from its current revision.

• egg

Introduction

Sparse vectors are vectors that grow as large as they need to. That is, they can be indexed by arbitrarily large nonnegative integers. The implementation allows for arbitrarily large gaps by arranging the entries in a tree.

Usage

`(require-extension sparse-vectors)`

If you have the numbers extension installed then this extension will be built with an additional variant that supports bignum indices:

`(require-extension big-sparse-vectors)`

API

```[procedure] (make-sparse-vector [DEFAULT]) -> sparse-vector
[procedure] (sparse-vector? x) -> boolean
[procedure] (sparse-vector-ref sparse-vector k) -> value
[procedure] (sparse-vector-set! sparse-vector k value)
[procedure] (sparse-vector->list sparse-vector) -> list  ```

make-sparse-vector, sparse-vector-ref and sparse-vector-set! are analogous to make-vector, vector-ref and vector-set!, except that the indices passed to sparse-vector-ref and sparse-vector-set! can be arbitrarily large.

The optional DEFAULT argument to the make-sparse-vector procedure specifies the default value for indices whose elements have not been set. If the element at index i has not been set, sparse-vector-ref returns DEFAULT or #f, if DEFAULT was not specified when creating the vector.

sparse-vector->list is for debugging: It returns a list of the consecutive elements in a sparse vector from 0 to the highest element that has been set. Note that the list will also include all the #f elements for the unset elements.

Authors

Richard Kelsey and Jonathan Rees

```Copyright (c) 1993-2006 Richard Kelsey and Jonathan Rees

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. The name of the authors may not be used to endorse or promote products
derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.```

0.1
Initial release