sparse-array

A Clojure library designed to manipulate sparse arrays - multi-dimensional spaces accessed by indices, but containing arbitrary values rather than just numbers. For sparse spaces which contain numbers only, you're better to use a sparce matrix library, for example clojure.core.matrix.

Conventions:

For the purposes of this library, a sparse array shall be implemented as a map, such that all keys are non-negative members of the set of integers, except for the following keyword keys, all of which are expected to be present:

1. :dimensions The number of dimensions in this array, counting the present one (value expected to be a real number);
2. :coord The coordinate of the dimension represented by the current map (value expected to be a keyword);
3. :content What this map contains; if the value of :dimensions is one, then :data; otherwise, an ordered sequence of the coordinates of the dimensions below this one.

Thus an array with a single value 'hello' at coordinates x = 3, y = 4, z = 5 would be encoded:

{:dimensions 3
 :coord :x
 :content [:y :z]
 3 {:dimensions 2
    :coord :y
    :content [:z]
    4 {:dimensions 1
       :coord :z
       :content :data
       5 "hello"
     }
    }
  }

At the present stage of development, where the expectations of an operation are violated, nil is returned and no exception is thrown. However, it's probable that later there will be at least the option of thowing specific exceptions, as otherwise debugging could be tricky.

Usage

FIXME

License

Copyright © 2019 Simon Brooke

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.