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[英]Combining MultiIndex columns with similar root names in Pandas/Python
[英]Python 3 Pandas Combining or merging columns with similar data
我有一個數據框,我試圖用性別列更新性別列
import pandas as pd
import numpy as np
df=pd.DataFrame({'Users': [ 'Al Gore', 'Ned Flonders', 'Kim jong un', 'Al Sharpton', 'Michele', 'Richard Johnson', 'Taylor Swift', 'Alf pig', 'Dick Johnson', 'Dana Jovy'],
'Gender': [np.nan,'Male','Male','Male',np.nan,np.nan, 'Female',np.nan,'Male','Female'],
'Sex': ['M',np.nan,np.nan,'M','F',np.nan, 'F',np.nan,np.nan,'F']})
產量
>>>
Gender Sex Users
0 NaN M Al Gore
1 Male NaN Ned Flonders
2 Male NaN Kim jong un
3 Male M Al Sharpton
4 NaN F Michele
5 NaN NaN Richard Johnson
6 Female F Taylor Swift
7 NaN NaN Alf pig
8 Male NaN Dick Johnson
9 Female F Dana Jovy
[10 rows x 3 columns]
因此,如果在“性別”列中為男性,則在性別列中將顯示為M。
到目前為止,這是我嘗試過的事情:
df['Sex2']=(df.Gender.isin(['Male']).map({True:'M',False:''}) +
df.Sex.isin(['M']).map({True:'M',False:''}) +
df.Sex.isin(['F']).map({True:'F',False:''})+
df.Gender.isin(['Female']).map({True:'F',False:''}))
print(df)
產量
[10 rows x 3 columns]
Gender Sex Users Sex2
0 NaN M Al Gore M
1 Male NaN Ned Flonders M
2 Male NaN Kim jong un M
3 Male M Al Sharpton MM
4 NaN F Michele F
5 NaN NaN Richard Johnson
6 Female F Taylor Swift FF
7 NaN NaN Alf pig
8 Male NaN Dick Johnson M
9 Female F Dana Jovy FF
[10 rows x 4 columns]
我幾乎明白了,但這可能不太有效
這是我想要的輸出
>>>
Gender Sex Users
0 NaN M Al Gore
1 Male M Ned Flonders
2 Male M Kim jong un
3 Male M Al Sharpton
4 NaN F Michele
5 NaN NaN Richard Johnson
6 Female F Taylor Swift
7 NaN NaN Alf pig
8 Male M Dick Johnson
9 Female F Dana Jovy
[10 rows x 3 columns]
是否可以使用某些合並或更新功能來做到這一點?
使用map
:
In [14]:
import pandas as pd
import numpy as np
df=pd.DataFrame({'Users': [ 'Al Gore', 'Ned Flonders', 'Kim jong un', 'Al Sharpton', 'Michele', 'Richard Johnson', 'Taylor Swift', 'Alf pig', 'Dick Johnson', 'Dana Jovy'],
'Gender': [np.nan,'Male','Male','Male',np.nan,np.nan, 'Female',np.nan,'Male','Female'],
'Sex': ['M',np.nan,np.nan,'M','F',np.nan, 'F',np.nan,np.nan,'F']})
In [15]:
df
Out[15]:
Gender Sex Users
0 NaN M Al Gore
1 Male NaN Ned Flonders
2 Male NaN Kim jong un
3 Male M Al Sharpton
4 NaN F Michele
5 NaN NaN Richard Johnson
6 Female F Taylor Swift
7 NaN NaN Alf pig
8 Male NaN Dick Johnson
9 Female F Dana Jovy
[10 rows x 3 columns]
In [16]:
# create a sex dict
sex_map = {'Male':'M', 'Female':'F'}
# update only those where sex is NaN, apply map to gender to fill in values
df.loc[df.Sex.isnull(),'Sex'] = df['Gender'].map(sex_map)
df
Out[16]:
Gender Sex Users
0 NaN M Al Gore
1 Male M Ned Flonders
2 Male M Kim jong un
3 Male M Al Sharpton
4 NaN F Michele
5 NaN NaN Richard Johnson
6 Female F Taylor Swift
7 NaN NaN Alf pig
8 Male M Dick Johnson
9 Female F Dana Jovy
[10 rows x 3 columns]
比較效果:
In [21]:
%timeit df['Sex2']=(df.Gender.isin(['Male']).map({True:'M',False:''}) + df.Sex.isin(['M']).map({True:'M',False:''}) + df.Sex.isin(['F']).map({True:'F',False:''})+ df.Gender.isin(['Female']).map({True:'F',False:''}))
100 loops, best of 3: 2.38 ms per loop
In [24]:
%timeit df.loc[df.Sex.isnull(),'Sex'] = df['Gender'].map(sex_map)
1000 loops, best of 3: 1.21 ms per loop
In [27]:
# without the NaN mask which is similar to what you are doing
%timeit df['Sex'] = df['Gender'].map(sex_map)
1000 loops, best of 3: 531 µs per loop
因此,在這個小樣本上,它速度更快,而對於更大的數據幀,由於使用了cython,它應該明顯更快。
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