[ Python 常見問題 ] How do I insert a column at a specific column index in pandas?

 Source From Here

Question
Can I insert a column at a specific column index in pandas?

view plaincopy to clipboardprint?

1. import pandas as pd  
2. df = pd.DataFrame({'l':['a','b','c','d'], 'v':[1,2,1,2]})  
3. df['n'] = 0  

This will put column n as the last column of df, but isn't there a way to tell df to put n at the beginning?

HowTo
see docs: http://pandas.pydata.org/pandas-docs/stable/genera...d/pandas.DataFrame.insert.html

using loc = 0 will insert at the beginning:

view plaincopy to clipboardprint?

1. df.insert(loc, column, value)  

For example:

view plaincopy to clipboardprint?

1. df = pd.DataFrame({'B': [1, 2, 3], 'C': [4, 5, 6]})  
2.   
3. df  
4. Out:   
5.    B  C  
6. 0  1  4  
7. 1  2  5  
8. 2  3  6  
9.   
10. idx = 0  
11. new_col = [7, 8, 9]  # can be a list, a Series, an array or a scalar     
12. df.insert(loc=idx, column='A', value=new_col)  
13.   
14. df  
15. Out:   
16.    A  B  C  
17. 0  7  1  4  
18. 1  8  2  5  
19. 2  9  3  6