Removing version information in IDs
Identifiers (IDs) in public databases often contain version information.
ENSG00000100644.16 from Ensembl and
NM_001243084.1 from RefSeq.
Such version information can be an obstacle to join entries from different databases.
So, version information should be trimmed before joining.
The file that contains such IDs with version information
id.txt can be converted by tiny Perl script like
% perl -i~ -pe 's/([^\.]+)\./$1/g' id.txt
Original file will be renamed to
id.txt~, and converted file is now named as