This function computes the relative expression profiles of any given gene expression set. The relative expression profile is being computed as follows:

$$f_s = ( e_s - e_min ) / ( e_max - e_min )$$

where $$e_min$$ and $$e_max$$ denote the minimum/maximum mean expression level over the developmental stages s. This linear transformation corresponds to a shift by $$e_min$$ and a subsequent shrinkage by $$e_max - e_min$$. As a result, the relative expression level $$f_s$$ of developmental stage s with minimum $$e_s$$ is 0, the relative expression level $$f_s$$ of the developmental stage s with maximum $$e_s$$ is 1, and the relative expression levels $$f_s$$ of all other stages s range between 0 and 1, accordingly.

RE(ExpressionMatrix)

## Arguments

ExpressionMatrix a numeric matrix representing a gene expression matrix for which the relative expression profile shall be computed.

## Value

a vector containing the relative expression profile of the correspnding data matrix.

## References

Domazet-Loso T and Tautz D. (2010). A phylogenetically based transcriptome age index mirrors ontogenetic divergence patterns. Nature (468): 815-818.

Quint M et al. (2012). A transcriptomic hourglass in plant embryogenesis. Nature (490): 98-101.

REMatrix, PlotRE

Hajk-Georg Drost

## Examples