a script that creates duplicate rows from columns in excel

Closed - This job posting has been filled and work has been completed.

Job Description

I need a script that would transpose an excel sheet with many columns into a sheet with 2 columns, but the 1st
e.g.
take the document
id | tag 1 | tag 2 | tag 3
112 | apples | cat | dog
eer | love | table | sometag

into

id | tag
112 | apples
112 | cat
112 | dog
eer | love
eer | table
eer | sometag

the sheet has ~500K rows and ~10 columns per row, so make sure your script can handle large amounts of data.