[英]How to replace values in a dataFrame by checking for a condition?
我有以下数据框:
A | Date1 | Date2
10 | 2/2/2016 | 3/2/2016
11 | 1/5/2016 | 1/5/2016
12 | 2/3/2016 | 2/3/2016
13 | 1/5/2016 | 3/2/2013
如果Date1中的值等于Date2 ,我想将A列中的值设为0 。 最终结果:
A | Date1 | Date2
10 | 2/2/2016 | 3/1/2016
0 | 1/5/2016 | 1/5/2016
0 | 2/3/2016 | 2/3/2016
13 | 1/5/2016 | 3/2/2013
我想这样做而不编写for循环。 我可以使用申请吗?
您可以重新创建我的df:
df = pd.DataFrame([[10, "2/2/2016", "3/2/2016" ] , [11, "1/5/2016", "1/5/2016"] , [12 , "2/3/2016" , "2/3/2016" ] , [13, "1/5/2016", "3/2/2013"]])
df.columns = ['A','B','C']
使用mask
:
import pandas as pd
df = pd.DataFrame([[10, "2/2/2016", "3/2/2016" ] ,
[11, "1/5/2016", "1/5/2016"] ,
[12 , "2/3/2016" , "2/3/2016" ] ,
[13, "1/5/2016", "3/2/2013"]])
df.columns = ['A','B','C']
print (df)
A B C
0 10 2/2/2016 3/2/2016
1 11 1/5/2016 1/5/2016
2 12 2/3/2016 2/3/2016
3 13 1/5/2016 3/2/2013
df['A'] = df.mask(df.B == df.C, 0)
print (df)
A B C
0 10 2/2/2016 3/2/2016
1 0 1/5/2016 1/5/2016
2 0 2/3/2016 2/3/2016
3 13 1/5/2016 3/2/2013
解where
:
df['A'] = df.where(df.B != df.C, 0)
print (df)
A B C
0 10 2/2/2016 3/2/2016
1 0 1/5/2016 1/5/2016
2 0 2/3/2016 2/3/2016
3 13 1/5/2016 3/2/2013
使用jezrael的设置
import pandas as pd
df = pd.DataFrame([[10, "2/2/2016", "3/2/2016" ] ,
[11, "1/5/2016", "1/5/2016"] ,
[12 , "2/3/2016" , "2/3/2016" ] ,
[13, "1/5/2016", "3/2/2013"]])
df.columns = ['A','B','C']
loc
df.loc[df.B == df.C, 'A'] = 0
print df
A B C
0 10 2/2/2016 3/2/2016
1 0 1/5/2016 1/5/2016
2 0 2/3/2016 2/3/2016
3 13 1/5/2016 3/2/2013
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