CODEWITHSUNDEEP
javasparse-array
Jack
Jack

Reputation: 133577

Which is the best way to implement a sparse vector in Java?

Which is the best way to implement a sparse vector in Java?

Of course the good thing would be to have something that can be manipulated quite easily (normalization, scalar product and so on)

Thanks in advance

Upvotes: 1

Views: 4013

Answers (3)

Chad Okere
Chad Okere

Reputation: 4578

MTJ has a Sparse Vector class. It has norm functions (1-norm 2-norm and ∞-norm) and dot product functions.

Upvotes: 3

Vladimir Kostyukov
Vladimir Kostyukov

Reputation: 2552

You can also try to look at la4j's CompressedVector implementation. It uses pair of arrays: array of values and array of their indicies. And with binary search on top of that it just flies. So, this implementation guarantees O(log n) running time for get/set operations.

Just a brief example

Vector a = new CompressedVector(new double[]{ 1.0, 2.0, 3.0 }).

// calculates L_1 norm of the vector
double n = a.norm();

// calculates the sum of vectors elements
double s = a.fold(Vectors.asSumAccumulator(0.0));

Upvotes: 3

trashgod
trashgod

Reputation: 205785

JScience has a SparseVector implementation that is part of its linear algebra package.

Upvotes: 3

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