How To Sort Row Index Case-insensitive Way In Pandas Dataframe

I have the following data: Set Coolthing Route Organ Up Down set4 Pam3CSK4 ID LL 81 60 set4 Poly_IC ID LL 542 92 set4 Poly_IC ID MM 73 73 set4 cdiGMP ID MM 143 78 set4 Poly_IC ID B

Solution 1:

Building on @Marius case_insensitive_order, a single liner using reindex

In [63]: df.reindex(sorted(df.index, key=lambda x: x.lower()))
Out[63]:
          Up            Down
          BB   LL   MM    BB  LL  MM
cdiGMP    900143129078
Pam3CSK4   08100600
Poly_IC   3254273829273

Solution 2:

You can force this by using the new CategoricalIndex (new in 0.16.1, I think), but I'm not sure if it's a great idea as it may have unpredictable effects:

case_insenstive_order = sorted(df.index, key=lambda x: x.lower())
case_insenstive_order
Out[4]: ['cdiGMP', 'Pam3CSK4', 'Poly_IC']

df.index = pd.CategoricalIndex(df.index, 
                               categories=case_insenstive_order, 
                               ordered=True)
df.sort_index()
Out[7]: 
          Up           Down        
          BB   LL   MM   BB  LL  MM
cdiGMP    900143129078
Pam3CSK4   08100600
Poly_IC   3254273829273

Solution 3:

I consider this a valid answer too:

df = df.iloc[df.index.str.lower().argsort()]

However, reindex certainly works a bit faster:

%timeit df.reindex(sorted(df.index, key=lambda x: x.lower()), copy=True)
1000 loops, best of3: 794 µs per loop

%timeit df.iloc[df.index.str.lower().argsort()]
1000 loops, best of3: 850 µs per loop

I tested here with pandas 0.20.3 and python2 on a table that had 500 rows and about 50 columns.