Ordering the column values in pandas

Question

In the following dataframe, in each row, I want name1 value to be smaller values among name1 and name2.

data = {'name1': ['Jason', 'Molly', 'Tina', 'yuma', 'Amy'],
        'name2': ['Cochice', 'Pima', 'Santa', 'Maria', 'Yuma'],
        'val': [12, 22, 4, 9, 7],
        'db' : ['xx','yy', 'zz', 'mm', 'aa']}
df = DataFrame(data)
df


db  name1   name2   val
xx  Jason   Cochice 12
yy  Molly   Pima    22
zz  Tina    Santa   4
mm  yuma    Maria   9
aa  Amy Yuma    7

As far as I know sorting can be done by rows only. How to arrange values in this manner?

The expected output is:

db  name1   name2   val
xx  Cochice Jason   12
yy  Molly   Pima    22
zz  Santa   Tina    4
mm  Amy     Maricopa    9
aa  Amy     Yuma    7

jezrael · Accepted Answer · 2016-12-04 10:07:12Z

2

You can use apply with sorted, but first set_index and last reset_index:

print (df.set_index('val').apply(sorted, axis=1).reset_index())
   val    name1  name2
0    2  Cochice  Jason
1    2    Molly   Pima
2    3    Santa   Tina
3    3      Amy  Maria
4    3      Amy   Yuma

Similar solution with np.sort:

print (df.set_index('val').apply(np.sort, axis=1).reset_index())
   val    name1  name2
0    2  Cochice  Jason
1    2    Molly   Pima
2    3    Santa   Tina
3    3      Amy  Maria
4    3      Amy   Yuma

If multiple columns use subset:

df[['name1','name2']] = df[['name1','name2']].apply(np.sort, axis=1)
print (df)
   db    name1  name2  val
0  xx  Cochice  Jason    2
1  yy    Molly   Pima    2
2  zz    Santa   Tina    3
3  mm      Amy  Maria    3
4  aa      Amy   Yuma    3

edited Dec 4, 2016 at 10:07

answered Dec 4, 2016 at 9:51

jezrael

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1 Comment

learner Over a year ago

Works perfect but I think I was not very clear. I have other columns as well. I need this operation on only name1 and name2 keeping all other columns unchanged. Chaged the OP

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