pandas之dataframe去掉冗余行以及左连接合并dataframe

去掉冗余行

重现冗余数据

zylMBP:~ zhangyalin$ python3
Python 3.6.5 (v3.6.5:f59c0932b4, Mar 28 2018, 03:03:55)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import pandas as pd
>>> df = pd.DataFrame({"A":["foo", "foo", "foo", "bar"]})
>>> print(df)
A
0  foo
1  foo
2  foo
3  bar

三种方式去冗余数据

方式1

>>> df.drop_duplicates(subset=['A'], keep=False)
A
3  bar
>>>

方式2

>>> df.drop_duplicates(subset=['A'], keep='first')
A
0  foo
3  bar
>>>

方式3

>>> df.drop_duplicates(subset=['A'], keep='last')
A
2  foo
3  bar
>>>

pandas左连接两个dataframe

result = pd.merge(left, right, how='left', on=['key1', 'key2'])

参考