geneSetSource
source to be used to construct the
list of pathway categories; for public data sources, the
user can specify a string (one of 'GOBP', 'GOMF', 'GOCC',
'KEGG' or 'REACTOME') and BioC packages will be used to
construct the list of pathway categories; for non-public
data sources, the user can pass the pathway data as a
dataframe with (at least) the following four columns:
PATHWAYID, TAXID, PATHWAYNAME and GENEID. It is assumed
all columns are of type character. The 'geneSetSource'
argument should be the same as the argument provided to
the getGeneSets function; defaults to NULL