Unpivot a table using Python/Pandas

unpivot.py

#!/usr/bin/env python

import os
import numpy
import pandas

xlsx = './workbook.xlsx'
df = pandas.read_excel(open(xlsx,'rb'), sheetname=0)

id_vars = ['Department', 'Category', 'Item']
value_vars = [item for item in list(df.columns.values) if item not in list(id_vars)]

df2 = pandas.melt(df,
                  id_vars=id_vars,
                  value_vars=value_vars,
                  var_name=['Store'],
                  value_name='Sales')

parts = os.path.splitext(xlsx)
oxlsx = parts[0] + '_unpivoted' + parts[1]
writer = pandas.ExcelWriter(oxlsx)
df2.to_excel(writer, sheet_name='Sheet1', index=False)
writer.save()