Data Frame Subset

Question

Below I have code listed. I have data frame a which has many columns I am attempting to query a subset of two columns 'Rank' & 'Country' from data frame a into my new data frame. Why does this code not work?

df= a['Rank', 'Country']

If I use

df=a['Rank']

It works fine.

Have a look at their documentation: pandas.pydata.org/pandas-docs/stable/indexing.html#basics This should answer your question. — holzkohlengrill
– holzkohlengrill, Commented May 26, 2017 at 13:42

jezrael · Accepted Answer · 2017-05-26 13:37:49Z

3

Need another []:

df= a[['Rank', 'Country']]

what is same as, but it is less typing:

df = a.loc[:, ['Rank', 'Country']]

Sample:

a = pd.DataFrame({'Rank':[1,2,3],
                   'Country':[4,5,6],
                   'C':[7,8,9]})

print (a)
   C  Country  Rank
0  7        4     1
1  8        5     2
2  9        6     3

df = a.loc[:, ['Rank', 'Country']]
print (df)
   Rank  Country
0     1        4
1     2        5
2     3        6

df = a[['Rank', 'Country']]
print (df)
   Rank  Country
0     1        4
1     2        5
2     3        6

You can also check docs:

You can pass a list of columns to [] to select columns in that order.

Also for select column to one column DataFrame use [] too:

df = a[['Rank']]
print (df)
   Rank
0     1
1     2
2     3

but for Series:

s = a['Rank']
print (s)
0    1
1    2
2    3
Name: Rank, dtype: int64

edited May 26, 2017 at 13:37

answered May 26, 2017 at 13:32

jezrael

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