[ 常見問題 ] How to select all columns, except one column in pandas?

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Question
I have a dataframe look like this:

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1. import pandas  
2. import numpy as np  
3. df = DataFrame(np.random.rand(4,4), columns = list('abcd'))  
4. df  
5.       a         b         c         d  
6. 0  0.418762  0.042369  0.869203  0.972314  
7. 1  0.991058  0.510228  0.594784  0.534366  
8. 2  0.407472  0.259811  0.396664  0.894202  
9. 3  0.726168  0.139531  0.324932  0.906575  

How I can get all columns except column b?

HowTo
When the columns are not a MultiIndex, df.columns is just an array of column names so you can do:

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1. df.loc[:, df.columns != 'b']  
2.   
3.           a         c         d  
4. 0  0.561196  0.013768  0.772827  
5. 1  0.882641  0.615396  0.075381  
6. 2  0.368824  0.651378  0.397203  
7. 3  0.788730  0.568099  0.869127  

Or you can leverage API:difference:

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1. df[df.columns.difference(['b'])]  
2.   
3. Out:   
4.           a         c         d  
5. 0  0.427809  0.459807  0.333869  
6. 1  0.678031  0.668346  0.645951  
7. 2  0.996573  0.673730  0.314911  
8. 3  0.786942  0.719665  0.330833