manipulating_lists/questions.rst
author Puneeth Chaganti <punchagan@fossee.in>
Wed, 01 Dec 2010 16:51:35 +0530
changeset 522 d33698326409
permissions -rw-r--r--
Renamed all LOs to match with their names in progress.org.

Objective Questions
-------------------

.. A mininum of 8 questions here (along with answers)

1. Given the list primes, ``primes = [2, 3, 5, 7, 11, 13, 17, 19, 23,
   29]``, How do you obtain the last 4 primes?

   Answer: primes[-4:]

#. Given the list primes, ``primes = [2, 3, 5, 7, 11, 13, 17, 19, 23,
   29]``, What is the output of ``primes[::5]``?

   Answer: ``[2, 13]``
   
#. Given a list, p, of unknown length, obtain the first 3 (or all, if
   there are fewer) characters of it. 

   Answer: p[:3]

#. The method ``reverse`` reverses a list in-place. True or False?

   Answer: True
   
#. ``reversed`` function reverses a list in-place. True or False?

   Answer: False

#. Given the list ``p = [1, 2, 3]``. p[4] produces an IndexError. True
   or False?

   Answer: True

#. Given the list ``p = [1, 2, 3]``. p[:4] produces an IndexError. True
   or False?

   Answer: False

#. Given the list primes, ``primes = [2, 3, 5, 7, 11]``, What is the
   output of ``primes[::-1]``?

   Answer: [11, 7, 5, 3, 2]

#. Given the list primes, ``primes = [2, 3, 5, 7, 11]``, What is the
   output of ``primes[::-3]``?

   Answer: [11, 3]


Larger Questions
----------------

.. A minimum of 2 questions here (along with answers)

#. Given a list p. Append it's reverse to itself. 

   Answer::

      p = p + reversed(p)


#. Marks is a list containing the roll numbers of students followed by
   marks. [This is not a recommended way to hold the marks details,
   but the teacher knows only so much Python!] Now she wants to get
   the average of the marks. Help her do it. 

   Answer::

     marks = [1, 9, 2, 8, 3, 3, 4, 10, 5, 2]
     average = sum(marks[1::2])/len(marks[1::2])