Data frames of features (peaks, genes...) coordinates on genome.
A data frame with the following columns:
CHROM
Chromosome names in character format, e.g. "15", "X" (character).
start
Start positions (integer).
end
End positions (character).
id
Unique identifiers, e.g. gene name "CDH1" or peak identifier
CHROM_start_end "1_1600338_1600838" (character).