doublesorting.py

products = """A,10,20
B,50,30
C,10,10
D,50,40
E,60,10"""

product_lines = [product.split(',') for product in products.splitlines()]
# sorting by INCREASING price 
per_price = sorted(product_lines, key = lambda product: product[2])
# [['C', '10', '10'], ['E', '60', '10'], ['A', '10', '20'], ['B', '50', '30'], ['D', '50', '40']]
# Then sorting according to the second key decreasing, the price being already ordered will stay sorted.
per_popularity = sorted(per_price, key = lambda product: product[1], reverse=True)
# [['E', '60', '10'], ['B', '50', '30'], ['D', '50', '40'], ['C', '10', '10'], ['A', '10', '20']]