Combine two lists and then sort each column

Question

I have a file [ Name Age Marks] . I have stored each values of Name in a list1 . Marks in list2. I have combined both lists using zip function in python:

 list3 =[]
 list3 = zip(list1,list2)

Eg: list3 = ((Steve,32),(David,65),(Ram,43),(Mary,87)) Now I want to sort list3 in descending order of marks. So kindly help how to proceed with this. I am new to python. Thanks for your time and consideration. Awaiting response

Variable names should be descriptive. Instead of list1, why not names? And instead of list2, why not marks? — mhlester
– mhlester, Commented Apr 24, 2014 at 16:54
You don't need to do list3 =[] before assigning it to zip, by the way. I'm guessing you're doing it in order to "declare" that list3 is a list. But in Python, variables do not need declaration; you could have done list3 = 2342 instead, and everything would still work the same way. So you may as well not put anything before list3 = zip(... — Kevin
– Kevin, Commented Apr 24, 2014 at 16:59
possible duplicate of How can I "zip sort" parallel numpy arrays? — JasonMArcher
– JasonMArcher, Commented Apr 24, 2014 at 17:15

falsetru · Accepted Answer · 2014-04-24 16:53:25Z

2

sorted, list.sort accept optional key function. Return values of the function are used for comparison.

>>> list3 = [('Steve',32),('David',65),('Ram',43),('Mary',87)]
>>> sorted(list3, key=lambda item: item[1])
[('Steve', 32), ('Ram', 43), ('David', 65), ('Mary', 87)]

>>> sorted(list3, key=lambda item: -item[1]) # negate the return value.
[('Mary', 87), ('David', 65), ('Ram', 43), ('Steve', 32)]

>>> sorted(list3, key=lambda item: item[1], reverse=True) # using `reverse`
[('Mary', 87), ('David', 65), ('Ram', 43), ('Steve', 32)]

answered Apr 24, 2014 at 16:53

falsetru

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1 Comment

user3569820 Over a year ago

Thank you, it worked. I would like to know if I have a list :

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