Description: COBRA decomposes a (partial) gene co-expression matrix as a linear combination of covariate-specific components. It can be applied for batch correction, differential co-expression analysis controlling for variables, and to understand the impact of variables of interest to the observed co-expression.

## Arguments

- X
: design matrix of size (n, q), n = number of samples, q = number of covariates

- expressionData
: gene expression as a matrix of size (g, n), g = number of genes

- method
: if pearson, the decomposition of the co-expression matrix is compouted. If pcorsh, COBRA decomposes the regularized partial co-expression

Outputs: