od.concat code example

Example 1: concat pandas python

>>> s1 = pd.Series(['a', 'b'])
>>> s2 = pd.Series(['c', 'd'])
>>> pd.concat([s1, s2])
0    a
1    b
0    c
1    d
dtype: object

Example 2: pandas concat and reset index

train_df = pd.concat(train_class_df_list, ignore_index=True)