R Under development (unstable) (2025-04-16 r88149 ucrt) -- "Unsuffered Consequences"
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> stopifnot(require(hdi))
Loading required package: hdi
Loading required package: scalreg
Loading required package: lars
Loaded lars 1.3

> 
> ## this is the example code of the help file of clusterGroupBound
> 
> ## Create a regression problem with correlated design (n = 10, p = 3):
> ## a block of size 2 and a block of size 1, within-block correlation is 0.99
> 
> set.seed(29)
> p   <- 3
> n   <- 10
> 
> Sigma <- diag(p)
> Sigma[1,2] <- Sigma[2,1] <- 0.99
> 
> x <- matrix(rnorm(n * p), nrow = n) %*% chol(Sigma)
> 
> ## Create response with active variable 1
> beta    <- rep(0, p)
> beta[1] <- 5
> 
> y  <- as.numeric(x %*% beta + rnorm(n))
> 
> out <- clusterGroupBound(x, y, nsplit = 4) ## use larger value for nsplit!

  5    3 member(s)	 with lower bound 3.642297
  3    1 member(s)	 with lower bound 0

  4    2 member(s)	 with lower bound 3.057924
  1    1 member(s)	 with lower bound 0

  2    1 member(s)	 with lower bound 0


> 
> ## Plot and print the hierarchical group-test
> plot(out)
> print(out)
lower l1-norm group bounds in a hierarchical clustering:
- lower bound on l1-norm of *all* regression coefficients: 3.642
- only 1 significant non-overlapping cluster with 2 members
 > out$members
[[1]]
[1] 1

[[2]]
[1] 2

[[3]]
[1] 3

[[4]]
[1] 1 2

[[5]]
[1] 1 2 3

> out$lowerBound
[1] 0.000000 0.000000 0.000000 3.057924 3.642297
> 
> proc.time()
   user  system elapsed 
   4.20    4.39    8.56