SSSP Worked Example

In sssp: Semi-Symmetric Sparse Projection

library(sssp)
v <- c(10, -1, 2, 3, 9, 0, -4, -8, 7, 6)
groups <- c(3, 4, 3)
res <- sssp_project(v, groups, r = 3, s = 6)
print(res)

Here v is (v \in \mathbb{R}^{10}), groups encodes (\mathcal{L}_1={1,2,3}), (\mathcal{L}_2={4,5,6,7}), and (\mathcal{L}_3={8,9,10}), r is the group sparsity level (r), and s is the sparsity level (s). With (r=p=3), the group sparsity restriction is removed and the feasible exact-(s) tuple count is 13.

res_r2 <- sssp_project(v, groups, r = 2, s = 6)
print(res_r2)

The same projection call accepts a list of 1-based index vectors. The next example uses non-uniform groups of sizes 2, 6, and 4, with (|\mathcal{L}_1| < s).

v2 <- c(4, -3, 5, 2, -6, 1, 7, -8, 0.5, 9, -2, 3)
groups2 <- list(c(1, 4), c(2, 3, 5, 8, 9, 10), c(6, 7, 11, 12))
res2 <- sssp_project(v2, groups2, r = 2, s = 5)
print(res2)

sssp documentation built on Sept. 5, 2026, 5:08 p.m.