How duplicated items can be deleted from dataframe in pandas

Question

I have the following data:

userid itemid
  1       1
  1       1
  1       3
  1       4
  2       1
  2       2
  2       3

How can I drop duplicated items (not the index) to make the following DataFrame:

userid itemid
  1       1
  1       3
  1       4     
  2       1
  2       2
  2       3

Can someone help me?

import pandas as pd    
df = pd.DataFrame({'userid':[1,1,1,1, 2,2,2],
                   'itemid':[1,1,3,4, 1,2,3] })

Answer 1

The best way would be to use drop_duplicates(). If you have a larger DataFrame and only want those two columns checked, set subset equal to the combined columns you want checked.

df = df.drop_duplicates()

or

df = df.drop_duplicates(subset=['userid', 'itemid'])

Answer 2

To avoid reassignment, use (inplace = True)

df.drop_duplicates(inplace=True)

This is same as

df = df.drop_duplicates()

Answer 3

df.groupby(df.index).first() 

worked for me.

Answer 4

Use drop_duplicates() of pandas:

import pandas as pd    
df = pd.DataFrame({'userid':[1,1,1,1, 2,2,2],
                   'itemid':[1,1,3,4, 1,2,3] })
print(df)
print()
print(df.drop_duplicates())

Consider that drop won't change the df itself and just pass a new data frame which has dropped the specified row(s). If you want to change the df itself set inside parameter to True.

Answer 5

Using the following code:

df = df.drop_duplicates(['userid','itemid'])