I have a dataframe that looks like:
Name Previous Name
Alice NaN
Charlie Bob
Bob Alice
Fred Eddy
Danny Charlie
Eddy Dan
I would like to sort the dataframe so that is looks like:
Name Previous Name
Alice NaN
Bob Alice
Charlie Bob
Danny Charlie
Eddy Danny
Fred Eddy
I know the boolean test involves something like
dataframe['Value'] = dataframe['PreviousValue'].shift(1)
But how can I use that as a sort criteria?
EDIT: Changed example from letters to names
Sort of values, then shift:
df = df.sort_values('Value')
df['Previous Value'] = df['Value'].shift()
Output:
Value Previous Value
0 A NaN
2 B A
1 C B
4 D C
5 E D
3 F E
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