diss_correlation: Correlation dissimilarity method constructor

In resemble: Similarity Retrieval and Local Learning for Spectral Chemometrics

Correlation dissimilarity method constructor

Description

Creates a configuration object that fully specifies a correlation (or moving correlation) dissimilarity method. Pass the result to dissimilarity() to compute the dissimilarity matrix.

Usage

diss_correlation(ws = NULL, center = TRUE, scale = FALSE)

Arguments

ws	Either NULL (default) or an odd integer greater than 2. When NULL, standard Pearson correlation dissimilarity is used. When an odd integer is provided, a moving (rolling) correlation dissimilarity is computed using a window of that size.
center	Logical. Should the data be mean-centered before computing dissimilarities? Centering is applied jointly to Xr and Xu (if provided) based on their combined column means. Default is TRUE.
scale	Logical. Should the data be scaled (divided by column standard deviations) before computing dissimilarities? Scaling is applied jointly to Xr and Xu (if provided). Default is FALSE.

Details

The correlation dissimilarity between two observations x_i and x_j is:

d(x_i, x_j) = \frac{1}{2}(1 - \rho(x_i, x_j))

where \rho is the Pearson correlation coefficient. This is used when ws = NULL.

When ws is specified, the moving correlation dissimilarity is:

d(x_i, x_j; ws) = \frac{1}{2\,ws} \sum_{k=1}^{p - ws} \bigl(1 - \rho(x_{i,(k:k+ws)},\, x_{j,(k:k+ws)})\bigr)

where ws is the window size and p is the number of variables.

Value

An object of class c("diss_correlation", "diss_method") — a list holding the validated method parameters. Intended to be passed to dissimilarity(), not used directly.

Parallel execution

The underlying C++ implementation uses OpenMP for parallel computation. Thread count is controlled by the OMP_NUM_THREADS environment variable. To limit threads (e.g., when calling from within a parallel backend):

Sys.setenv(OMP_NUM_THREADS = 1)

Author(s)

Leonardo Ramirez-Lopez

See Also

dissimilarity, diss_euclidean, diss_mahalanobis, diss_cosine

Examples

# Standard correlation dissimilarity
m <- diss_correlation()

# Moving correlation with window size 41
m <- diss_correlation(ws = 41)

# Without centering
m <- diss_correlation(center = FALSE)

resemble documentation built on April 21, 2026, 1:07 a.m.