cluster: lower.to.upper.tri.inds – R documentation

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lower.to.upper.tri.inds

Permute Indices for Triangular Matrices

Description

Compute index vectors for extracting or reordering of lower or upper triangular matrices that are stored as contiguous vectors.

Usage

lower.to.upper.tri.inds(n)
upper.to.lower.tri.inds(n)

Arguments

`n`	integer larger than 1.

Value

integer vector containing a permutation of 1:N where N = n(n-1)/2.

Examples

m5 <- matrix(NA,5,5)
m <- m5; m[lower.tri(m)] <- upper.to.lower.tri.inds(5); m
m <- m5; m[upper.tri(m)] <- lower.to.upper.tri.inds(5); m

stopifnot(lower.to.upper.tri.inds(2) == 1,
          lower.to.upper.tri.inds(3) == 1:3,
          upper.to.lower.tri.inds(3) == 1:3,
     sort(upper.to.lower.tri.inds(5)) == 1:10,
     sort(lower.to.upper.tri.inds(6)) == 1:15)

cluster

"Finding Groups in Data": Cluster Analysis Extended Rousseeuw et al.

v2.1.2

GPL (>= 2)

Authors

Martin Maechler [aut, cre] (<https://orcid.org/0000-0002-8685-9910>), Peter Rousseeuw [aut] (Fortran original, <https://orcid.org/0000-0002-3807-5353>), Anja Struyf [aut] (S original), Mia Hubert [aut] (S original, <https://orcid.org/0000-0001-6398-4850>), Kurt Hornik [trl, ctb] (port to R; maintenance(1999-2000), <https://orcid.org/0000-0003-4198-9911>), Matthias Studer [ctb], Pierre Roudier [ctb], Juan Gonzalez [ctb], Kamil Kozlowski [ctb], Erich Schubert [ctb] (fastpam options for pam(), <https://orcid.org/0000-0001-9143-4880>), Keefe Murphy [ctb] (volume.ellipsoid({d >= 3}))

Initial release

2021-04-16