[FIXED] Sorting a dataframe by index

Issue

I have a dataframe called df that is indexed by date which I am trying to sort oldest date to newest.

I have tried to use both:

df = df.sort(axis=1)

and:

df = df.sort_index(axis=1)

but as you can see from the date order in the following df tail the dates have not been sorted into date order.

                            wood_density  
date                                      
2016-01-27                        5.8821  
2016-01-28                        5.7760  
2015-12-25                           NaN  
2016-01-01                           NaN  
2015-12-26                           NaN  

What can I try to resolve this?

Solution

Use sort_index to sort the index:

In [19]:

df = df.sort_index()
df
Out[19]:
            wood_density
date                    
2015-12-25           NaN
2015-12-26           NaN
2016-01-01           NaN
2016-01-27        5.8821
2016-01-28        5.7760

sort, which is deprecated by sort_values or sort_index sorts on row labels by default axis=0 so it would've worked if you didn't pass this:

In [21]:
df.sort()

Out[21]:
            wood_density
date                    
2015-12-25           NaN
2015-12-26           NaN
2016-01-01           NaN
2016-01-27        5.8821
2016-01-28        5.7760

Answered By - EdChum