biomaRt包

library(biomaRt)
# list database
listMarts()
# get genome of species in the database
mart <- useMart('ensembl')
list_db <- listDatasets(mart)
# list info about the genome
list_attr <- listAttributes(mus)
# get the info you want, it's an example of mouce
attributes = c(
  "ensembl_gene_id",
  "mgi_symbol",
  "transcript_length"
)
mus_info <- getBM(attributes = attributes, mart = mus)
head(mus_info)