README.md

sparse_array

Noir library that implements efficient sparse arrays, both constant (SparseArray) and mutable (MutSparseArray)

Benchmarks

TODO

Installation

In your Nargo.toml file, add the version of this library you would like to install under dependency:

[dependencies]
sparse_array = { tag = "v0.1.0", git = "https://github.com/noir-lang/sparse_array" }

sparse_array

Usage

use dep::sparse_array::{SparseArray, MutSparseArray}

// a sparse array of size 10,000 with 10 nonzero values
fn example_sparse_array(nonzero_indices: [Field; 10], nonzero_values: [Field; 10]) {
    let sparse_array_size = 10000;
    let array: SparseArray<10, Field> = SparseArray::create(nonzero_indices, nonzero_values, sparse_array_size);

    assert(array.get(999) == 12345);
}

// a mutable sparse array that can contain up to 10 nonzero values
fn example_mut_sparse_array(initial_nonzero_indices: [Field; 9], initial_nonzero_values: [Field; 9]) {
    let sparse_array_size = 10000;
    let mut array: MutSparseArray<10, Field> = MutSparseArray::create(nonzero_indices, nonzero_values, sparse_array_size);

    // update element 1234 to contain value 9999
    array.set(1234, 9999);

    // error, array can only contain 10 nonzero values
    array.ser(10, 888);
}

Costs

Constructing arrays is proportional to the number of nonzero entries in the array and very small ~10 gates per element (plus the cost of initializing range tables if not already done so)

Reading from SparseArray is 14.5 gates Reading and writing to MutSparseArray is ~30 gates