how to sort numbers in a descending order in python?

Question

I have the following code and I want to sort the value of metal in a descending order, I can call each number of them by using the name of the mealtal . the name that I gave for it . for example if I want to call the value of platinum I can use "platinum.valuePerBar" note that I have my own object which called RIT_object and I can put the type of each argument in the class as you can see in the code

from rit_object import *            # rit_object class

class Metal(rit_object):
    """
    Represents a single metal type, composed of:
    :slot name (str): The name of the metal
    :slot totalBars (int): The total number of bars
    :slot weightPerBar (int): The weight of a single bar
    :slot valuePerBar (int): The value of a single bar
    :slot valuePerWeight (float): The value per weight of the metal
    :slot barsTaken (int): The number of bars added to the satchel
    """

    __slots__ = ( 'name' ,  'totalBars' , 'valuePerBar' , 'weightPerBar' , 'barsTaken' )
    _types = ( str , int , int, int, float, int )




def createMetal(name, totalBars, weightPerBar, valuePerBar):
    """
    Create and return a new Metal object.
    :param name (str): The name of the metal
    :param totalBars (int): The total number of bars
    :param weightPerBar (int): The weight of a single bar
    :param valuePerBar (int): The value of a single bar
    :return: A newly initialized Metal object
    :rtype: Metal
    """
    platinum = Metal("platinum", 1, 1000, 6, 0)
    gold = Metal("gold", 1, 750, 5, 0)
    rhodium = Metal("rhodium", 1, 500, 5, 0)
    silver = Metal("silver", 1, 400, 4, 0)

def sortMetalsByValuePerBar(metals):
    """
    Sort the metals by value per bar using insertion sort.  The list of
    metals is modified in place to be ordered by value per bar.
    :param metals (list of Metal): The list of metals
    :return: None
    :rtype: NoneType
    """

how can I sort the value in a descending order ?

Answer 1

Try sorted with reverse parameter

sorted([1,2,3,4], reverse=True)

Relevant to your code:

from collections import namedtuple

Metal = namedtuple('Metal', 'name, totalBars, weightPerBar, valuePerBar')

platinum = Metal("platinum", 1, 1000, 100.23) 
gold = Metal("gold", 1, 750, 20.043) 
rhodium = Metal("rhodium", 1, 500, 10.93) 
silver = Metal("silver", 1, 400, 15.73)

metals = [platinum, silver, gold, rhodium]

# Sort by value in descending order
metals = sorted(metals, key=lambda x:x.valuePerBar, reverse=True)

for i in metals:
    print i.name, i.valuePerBar

[out]:

platinum 100.23
gold 20.043
silver 15.73
rhodium 10.93