L-infinity normalization (row-wise)

Scales each row of a numeric matrix by its L-infinity norm (row maximum). Rows whose maximum is at or below tolerance are left unchanged; nonzero entries in these rows are not replaced by zeros.

Usage

normalize.linf(X, tol = 0, backend = c("auto", "dense", "sparse"))

Arguments

X

Numeric matrix (samples x features).

tol

Finite numeric >= 0. Rows with maximum <= tol are not scaled. Default: 0 (exact zero only).

backend

Character. Matrix backend to use: "auto", "dense", or "sparse". The default "auto" preserves sparse input and otherwise uses the dense path.

Value

Numeric matrix of same dimensions as X, L-infinity normalized.

Details

Zero rows have undefined L-infinity direction. By convention, they are preserved as all-zero rows and yield NA in dominant-feature assignment. The pure dCST view places them in the rare category; the absorb view assigns them to its fallback retained state, if any. A nonzero row left unscaled because of tol still has a dominant feature.

Examples

X <- rbind(
  sample1 = c(A = 2, B = 1, C = 0),
  sample2 = c(A = 0, B = 0, C = 0)
)
Z <- normalize.linf(X)
Z
#>         A   B C
#> sample1 1 0.5 0
#> sample2 0 0.0 0
apply(Z, 1, max)
#> sample1 sample2 
#>       1       0