relaimpo provides several metrics for assessing relative importance in linear models. These can be printed, plotted and bootstrapped. The recommended metric is lmg, which provides a decomposition of the model explained variance into non-negative contributions. There is a version of this package available that additionally provides a new and also recommended metric called pmvd. If you are a non-US user, you can download this extended version from Ulrike Groempings web site.
With an activated Bioconda channel (see 2. Set up channels), install with:
conda install r-relaimpo
and update with:
conda update r-relaimpo
A Docker container is available at https://quay.io/repository/biocontainers/r-relaimpo.