How to compare the values of two columns and reorder the values based on comparison

This should work:

import pandas as pd data = [ { "Part No": 1, "A": 2, "B": 13, "cum of A": 2 }, { "Part No": 2, "A": 4, "B": 17, "cum of A": 6 }, { "Part No": 3, "A": 7, "B": 15, "cum of A": 13 }, { "Part No": 4, "A": 5, "B": 16, "cum of A": 18 }, { "Part No": 5, "A": 10, "B": 19, "cum of A": 28 }, { "Part No": 6, "A": 9, "B": 16, "cum of A": 37 }, { "Part No": 7, "A": 8, "B": 12, "cum of A": 45 } ] df = pd.DataFrame(data) smaller_indexes = len(df[df['B'] > df['cum of A']]) + 1 # check where B is larger than 'cum of A', take the length of that part of the dataframe and add 1 to get the index number of the last value to use for sorting df[:smaller_indexes] = df[:smaller_indexes].sort_values(by=['B']) # slice the dataframe by the found index number, and sort only that slice of the dataframe df['cum of A'] = df['A'].cumsum() #recount the cumsum of the entire dataframe 

This will output:

I know it is a little rough but if you want, you can use below:

#order the values in list def order(a): for i in range(len(a)): # print(i) b = a[i-1] - a[i] if b>0: temp = a[i-1] a[i-1] = a[i] a[i] = temp for j in range(i,0,-1): b = a[j-1] - a[j] if b>0: temp = a[j-1] a[j-1] = a[j] a[j] = temp return a b = [13,15,16,17,19,16,12] a = [2, 7, 5, 4, 10, 9, 8] #other list to append the last value if cum is greater than value of "b" after ordering b otherList = [] # isRecursive and indexToTake is for: # "And if there is still a higher value in cum of A than the values in B # among these reordered observations (first four parts), then part 4 will be # taken out from the list and put in a separate list." def solve(isRecursive, indexToTake): c = 0 for i in range(len(a)): c += a[i] #cum sum if c> b[i]: #check if cum is greater than the value of "b" at that index if isRecursive: if i >indexToTake: return otherList.append(b[indexToTake]) return b[0:i+1] = order(b[0:i+1]) solve(True, i) #check if the values at "b" are greater than cum after ordered until the indexToTake break solve(False, 0) #start solving