python - Get Rows based on distinct values from Column 2

53
votes

I am a newbie to pandas, tried searching this on google but still no luck. How can I get the rows by distinct values in column2?

For example, I have the dataframe bellow:

>>> df
COL1   COL2
a.com  22
b.com  45
c.com  34
e.com  45
f.com  56
g.com  22
h.com  45

I want to get the rows based on unique values in COL2

>>> df
COL1  COL2
a.com 22
b.com 45
c.com 34
f.com 56

So, how can I get that? I would appreciate it very much if anyone can provide any help.

1
pythonpandas

1 Answers

66
votes

Use drop_duplicates with specifying column COL2 for check duplicates:

df = df.drop_duplicates('COL2')
#same as
#df = df.drop_duplicates('COL2', keep='first')
print (df)
    COL1  COL2
0  a.com    22
1  b.com    45
2  c.com    34
4  f.com    56

You can also keep only last values:

df = df.drop_duplicates('COL2', keep='last')
print (df)
    COL1  COL2
2  c.com    34
4  f.com    56
5  g.com    22
6  h.com    45

Or remove all duplicates:

df = df.drop_duplicates('COL2', keep=False)
print (df)
    COL1  COL2
2  c.com    34
4  f.com    56