Pandas copying wrong values

[sandeep_ganga]

If we doesn't define ignore_index parameter, the concat/append will add second dataframe rows with the original index numbers it had, thus the new added rows have same index again which start with 0.

import pandas as pd
 
foo = pd.concat([pd.DataFrame({'foo': [10,20]}), pd.DataFrame({'foo': [30,40]})],ignore_index=True)
bar = pd.DataFrame({'bar': [1, 2, 3, 4]})
 
foo["bar"] = bar["bar"]
 
print((foo["bar"].values == bar["bar"].values).all())
print(foo)

Output:
True
   foo  bar
0   10    1
1   20    2
2   30    3
3   40    4

Best Regards,
Sandeep

GANGA SANDEEP KUMAR