Скачать или смотреть Pandas Duplicated - pd.Series.duplicated()

https://dataindependent.com/pandas/pa...

You may want to know if you have duplicate values in your DataFrame or Series. That's where Pandas Duplicated or pd.Series.Duplicated() comes in.

You use pandas duplicated when you want to remove repeat value, or flag them for further analysis.

To do this simply call: YourSeries.duplicated() to see which values appear more than once.

But you may want to treat your duplicates differently. Do you know want to know about the first duplicate? or the last? Pandas lets you pick. However, it's a bit counter intuitive, let's look at the options.

Method 1 - Keep='First': For when you want to mark all duplicates as true...EXCEPT for the first one.
Method 2 - Keep='Last': For when you want to mark all duplicates as true...EXCEPT for the last one.
Method 3 - Keep=False: For when you want to mark all duplicates as true.