Make a gurobi function for maximum coverage

[njtierney]

• Gurobi is really fast
• Gurobi is free and easier to get than CPLEX for academics
• Gurobi allows for sparse matrices
• There's a Gurobi R package/interface

Perhaps call the function max_coverage_gurobi

[njtierney]

Function is currently in beta, from commit https://github.com/njtierney/maxcovr/commit/56c8aad7eae50f35b84d7376ee4c69461773be45. Whilst this loads fine on my personal machine, it fails on both travis and appveyor. Appveyor states:

* checking package dependencies ... ERROR
Package required but not available: 'gurobi'

Whilst travis states:

3.18s$ Rscript -e 'deps <- devtools::dev_package_deps(dependencies = NA);devtools::install_deps(dependencies = TRUE);if (!all(deps$package %in% installed.packages())) { message("missing: ", paste(setdiff(deps$package, installed.packages()), collapse=", ")); q(status = 1, save = "no")}'
missing: gurobi
The command "Rscript -e 'deps <- devtools::dev_package_deps(dependencies = NA);devtools::install_deps(dependencies = TRUE);if (!all(deps$package %in% installed.packages())) { message("missing: ", paste(setdiff(deps$package, installed.packages()), collapse=", ")); q(status = 1, save = "no")}'" failed and exited with 1 during .
Your build has been stopped.

My understanding is that this occurs because the gurobi R package comes with the Gurobi software, and is not on CRAN, as described in their install instructions.

I assume that there is a way around this.

[njtierney]

Gurobi can be added to suggests to solve this.

For the moment, I have removed Gurobi, as I could not get it to work.

Current progress on gurobi is in issue #25 .