Hi! I have 2 questions about the
right_index=True seems to reset index for a table, but it is used for which table here, for churn or monthly_churn, it looks like to the monthly_churn. but we did not clarify to python, how did python know how to work?
2, we learned
pd.merge() in below format before. but it shows error.
churn = pd.merge(left=churn, right=monthly_churn, how="left", on="yearmonth", right_index=True)