rmSmallCompounds: Remove uniquitous compounds from a metabolic network
Description
This function removes uniquitous compounds (metabolites connected to numerous reactions)
from a metabolic network.These compounds are reaction cofactors and currency compounds,
such as ATP, CO2, etc. A path through these metabolites may not be bioloigcally meaningful.
The defualt small compound list is derived from Reactome, containing keeg.compound, pubchem.compound,
ChEBI and CAS identifiers.
How to handle small compounds. Either simply delete these vertices "remove" (default),
or make a separate vertex for each reaction they participate in "duplicate".
small.comp.ls
A list of small compounds to be used.
Value
A modified graph, with the small compounds removed or duplicated.