python 3.x - Pandas use variable for column names -

given following data frame:

import pandas pd import numpy np df = pd.dataframe({'a':[1,2,3],                    'b':[4,5,6],                    'c':[7,8,9]})  df        b   c 0   1   4   7 1   2   5   8 2   3   6   9 

how can access columns via variable?

i tried this:

cols='a','b' df[cols] 

...which resulted in this:

keyerror: ('a', 'b') 

bonus question: if data frame this?:

import pandas pd import numpy np df = pd.dataframe({'a':[1,2,3],                    'b':[4,5,6],                    'c':[7,8,9],                    'd':[1,3,5],                    'e':[5,3,6],                    'f':[7,4,3]})  df        b   c   d   e   f 0   1   4   7   1   5   7 1   2   5   8   3   3   4 2   3   6   9   5   6   3 

and wanted this?:

cols=['a','b'] cols2=['c','d'] df[cols,'f',cols2] 

thanks in advance!

you can try subset list of column names:

cols=['a','b'] print df[cols]     b 0  1  4 1  2  5 2  3  6 

it same as:

print df[['a','b']]     b 0  1  4 1  2  5 2  3  6 

bonus answer:

cols=['a','b'] cols2=['c','d']  allcols = cols + ['f'] + cols2 print df[allcols]     b  f  c  d 0  1  4  7  7  1 1  2  5  4  8  3 2  3  6  3  9  5