How to delete just some rows in a dataframe according with some fields condition in Python?-CodePudding

I need to keep just the first row of a dataframe for each group of values in a ordered column.

I need to transform this (first column is ordered by name):

a = [[1,'a'],[1,'c'],[1,'b'],[2,'c'],[2,'b'],[2,'a'],[3,'d']]

into this (just the first row for each value type in the first ordered column):

a = [[1,'a'],[2,'c'],[3,'d']]

CodePudding user response：

You can even get your desire output by convert to DF and by keeping the first value of each unique values of first column. lastly, converting back to list.

Code:

import pandas as pd

a = [[1,'a'],[1,'c'],[1,'b'],[2,'c'],[2,'b'],[2,'a'],[3,'d']]
a = pd.DataFrame(a).drop_duplicates(0, keep='first').values.tolist()