Query genetic positions in Marey Map R package

Question

[Famf]

I have a high dense set of SNP markers with physical positions. I want to interpolate physical positions (in bp) to genetic positions (in cM). I am using a genetic map from the same species in the MareyMap R package to do interpolations by using the option cubic splines. In this package there are options to query recombination rate (cM/Mb) from physical positions of each SNP but I do not see any option to query genetic positions in cM. Any suggestion how could I obtain genetic positions in cM for each marker?