DataFrame sorting based on a function of multiple column values

Question

Based on python, sort descending dataframe with pandas:

Given:

from pandas import DataFrame
import pandas as pd

d = {\'x\':[2,3,1,4,5],
     \'y\':[         


        

Answer 1

from pandas import DataFrame
import pandas as pd

d = {'one':[2,3,1,4,5],
     'two':[5,4,3,2,1],
     'letter':['a','a','b','b','c']}

df = pd.DataFrame(d)

#f = lambda x,y: x**2 + y**2
array = []
for i in range(5):
    array.append(df.ix[i,1]**2 + df.ix[i,2]**2)
array = pd.DataFrame(array, columns = ['Sum of Squares'])
test = pd.concat([df,array],axis = 1, join = 'inner')
test = test.sort_index(by = "Sum of Squares", ascending = True).drop('Sum of Squares',axis =1)

Just realized that you wanted this:

    letter  one  two
2      b    1    3
3      b    4    2
1      a    3    4
4      c    5    1
0      a    2    5