Trouble With Using Iloc In Pandas Dataframe With Hierarchical Index

I'm getting this ValueError whenever I try to give a list to iloc on a dataframe with a hierarchical index. I'm not sure if I'm doing something wrong or if this is a bug. I haven

Solution 1:

This was a bug and has been fixed in master (0.13), a temporary workaround is to use ix (!):

In[11]: df1.ix[[1, 3]]
Out[11]: 
            DEFay1.5445771.594976-0.084866by-0.4680740.673112-0.900547

In master, 0.13:

In[12]: df1.iloc[[1, 3]]
Out[12]: 
            DEFay1.5445771.594976-0.084866by-0.4680740.673112-0.900547

Solution 2:

It seems that pandas can't convert [[1,3]] to a proper MultiIndex. You might want to fill a bug in pandas issues tracker. The only workaround I found is to construct it manually, this way it is passed as is.

>>>tup = zip(*[['a','a','b','b'],['x','y','x','y']])>>>index = pd.MultiIndex.from_tuples(tup, names=['f','s'])>>>df = pd.DataFrame(np.random.randn(4, 4))>>>df
            0         1         2         3
f s
a x -0.334280  0.479317 -0.358416 -0.245807
  y  1.279348 -0.096336  0.100285  0.037231
b x -0.368452  0.219868 -0.103722 -0.575399
  y -0.813583 -0.042694  0.897361  1.636304
>>>idx = [i in [1,3] for i inrange(len(df.index))]>>>idx
[False, True, False, True]
>>>df.iloc[idx]
            0         1         2         3
f s
a y  1.279348 -0.096336  0.100285  0.037231
b y -0.813583 -0.042694  0.897361  1.636304

Other ways is to use get_level_values to access MultiIndex by level

>>> df.iloc[df.index.get_level_values('f') == 'a']0123
f s
a x -0.3342800.479317 -0.358416 -0.245807
  y  1.279348 -0.0963360.1002850.037231

On contrast, slice is correctly converted to MultiIndex:

>>> df.iloc[0:2,:]0123
f s
a x -0.334280.479317 -0.358416 -0.245807a y  1.279348 -0.0963360.1002850.037231