text_plain_output_1.png
train_df = train_transactions.merge(train_identity, how='left', on='TransactionID')
del train_transactions, train_identity

test_df = test_df.rename(columns=lambda x: '_'.join(x.split('-')))
train_df.set_index('TransactionID', inplace=True)
test_df.set_index('TransactionID', inplace=True)

train_df.to_pickle('train_df.pkl')
test_df.to_pickle('test_df.pkl')

train_df['id_38'].value_counts()