[Python] Pandas replace

문자열 치환 예제

df = pd.DataFrame({'A': [0, 1, 2, 3, 4],
                   'B': [5, 6, 7, 8, 9],
                   'C': ['Hello Lala', 'Hello Sam', 'Hello Jack', 'Hello John', 'Hello Maria']})
df["C"].str.replace("Hello", "Good morning")

''' Output
0    Good morning Lala
1    Good morning Sam
2    Good morning Jack
3    Good morning John
4    Good morning Maria
Name: C, dtype: object
'''

 

DICT 로 치환하는 예정

A Series에서 0을 10으로, 1을 100으로 치환한다. 

df = pd.DataFrame({'A': [0, 1, 2, 3, 4]})

df["A"].replace({0: 10, 1: 100})

''' Output
0     10
1    100
2      2
3      3
4      4
Name: C, dtype: object
'''

 

Nan타입 치환

# importing pandas as pd
import pandas as pd
  
# Making data frame from the csv file
df = pd.read_csv("nba.csv")
  
# will replace  Nan value in dataframe with value -99999 
df.replace(to_replace = np.nan, value =-99999)

 

정규식 사용 예제

#정규식 사용 예제
df = pd.DataFrame({'A': ['bat', 'foo', 'bait'],
                   'B': ['abc', 'bar', 'xyz']})

df.replace(to_replace=r'^ba.$', value='new', regex=True)

''' output
        A    B
0   new  abc
1   foo  new
2  bait  xyz
'''

 

 

참고 자료 : 

https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.replace.html