How to get the N nearest entries to the median in a Pandas series?

Question

For a Pandas Series:

ser = pd.Series([i**2 for i in range(9)])
print(ser)
0     0
1     1
2     4
3     9
4    16
5    25
6    36
7    49
8    64
dtype: int64

The median can be grabbed with ser.median(), which returns 16. How can the N entries around the median be grabbed? Something like:

print(ser.get_median_entries(3)) # N == 3; not real functionality
3     9
4    16
5    25
dtype: int64

Answer 1

You can find the abs difference between each value and the median and use sort_values():

ser[abs(ser - ser.median()).sort_values()[0:3].index]
#4    16
#3     9
#5    25
#dtype: int64

If you want it as a function, where n is an input variable:

def get_n_closest_to_median(ser, n):
    return ser[abs(ser - ser.median()).sort_values()[0:n].index]

print get_n_closest_to_median(ser, 3)
#4    16
#3     9
#5    25
#dtype: int64

You will probably have to add some error checking on the bounds.