首页 > > 详细

Assignment 4: Summary of Instructions and Overview

 Assignment 4: due at 8am on Monday, Nov 18, 2019

Summary of Instructions and Overview
Note Read the instructions carefully and follow them exactly
Assignment Weight 5.5% of your course grade
Due Date and time 8am on Monday, Nov 18, 2019
Important
As outlined in the syllabus, late submissions will not be accepted.
Any files with syntax errors will automatically be excluded from grading. Be sure to
test your code before you submit it
For all functions make sure you’ve written good docstrings that include type contract,
function description and the preconditions if any.
This is an individual assignment. Please review the Plagiarism and Academic Integrity policy presented in the first class,
i.e. read in detail pages 15 18 of the course outline (i.e. slides of Lecture 1). You can find that file on Brightspace under
Lecture 1. While at it, also review Course Policies on pages 13 and 14.
In addition to the assignment files specified later, if you used any code that you did not create/write yourself, your submission
will need to contain declaration-YOUR-FULL-NAME.txt file. Specifically:
About declaration-YOUR-FULL-NAME.txt file:
It needs to be a plane text file and it must contain references to any code you used that you did not write yourself, including
any code you got from a friend or internet or any other source or person. The only exclusion from that rule is the code that
we did in class or as part of the lab work. So here is what needs to be written in that file. In every question where you used
code from somebody else, you must write:
1. question number
2. copy-pasted parts of the code that were written by somebody else. That includes the code you found/were-given that you
then slightly modified.
3. whose code it is: name of a person or place on internet/book where you found it.
While you may not get points for that part of the question, with proper referencing there is no danger of finding yourself in
a plagiarizing position. Not including declaration-YOUR-FULL-NAME.txt will be taken as you declaring that all the code in
the assignment was written by you. Any student caught in plagiarism will receive zero for the whole assignment and will be
reported to the dean. Finally showing/giving any part of your assignment code to a friend also constitute plagiarism and the
same penalties will apply.
The goal of this assignment is to learn and practice the concepts covered thus far. In particular you will get more practice
with (2D) lists and functions. For one of the functions you will also need to learn how to prevent syntax errors i.e. crashes by
learning about try/except concept for handling exceptions. Given the goals of this assignment, you cannot user: dictionaries,
sets, deque, bisect module. You can though, and in fact should, use .sort or sorted functions.
As always, you can make multiple submissions, but only the last submission before the deadline will be graded.
For this assignment, you only need to submit one file, called a4_xxxxxx.py, where you changed xxxxxx to your student
number. (No need to submit a4_xxxxxx.txt as proof that you tested your function. By now we trust that you learnt and
understand the need and importance for testing your functions and code in general).
For this assignment, I provided you with starter code in file called a4_xxxxxx.py. Begin by replacing xxxxxx in the file
name with your student number. Then open the file. Your solution (code) for the assignment must go into that file in the
clearly indicated spaces. The file has main completely coded for you. Nothing else will go into the mail. It also has some
functions completely precoded for you. Your task will me to code the remaining functions. You are not allowed to delete or
comment-out any parts of the provided code. The only exception to that rule is the keyword pass. Some functions have that
keyword. You can remove it once you are done coding that function. You also must follow the instructions given in comments
and implied by docstrings. You are however allowed to add your own additional (helper) functions. In, fact you should add at
least one more function.
1
I have provided 5 text files to test and debug your code with as explained in the next section.
As always, your program must run without syntax errors. In particular, when grading your assignment, TAs will first open
your file a4_xxxxxx.py with IDLE and press Run Module. If pressing Run Module causes any syntax error, the grade for the
assignment becomes zero. Furthermore, for each function whose code is missing, I have provided below one or more tests to test
your functions with. To obtain a partial mark for these function your solutions may not necessarily give the correct answer on
these tests. But if your function gives any kind of Python error when run on the tests provided, that function will be marked
with zero points. Finally, each function has to be documented with docstrings.
There is also a4-more-example-runs.txt file, giving additional example runs to those given in the next section. The
behaviour of all example runs below and in a4-more-example-runs.txt should be considered as an implied requirement for
the assignment – as always.
Using global variables inside of functions is not allowed. If you do not know what that means, for now, interpret this to
mean that inside of your functions you can only use variables that are created in that function. For example, the following
code fragment would not be allowed, since variable x is not a parameter of function a_times(a) nor is it a variable created in
function a_times(a). It is a global variable created outside of all functions.
def a_times(a):
result=x*a
return result
x=float(input("Give me a number: "))
print(a_times(10))
1 Social Networks: friends recommendations and more – 100 points
Have you ever wondered how social networks, such as Facebook, recommend friends to you? Most of the social networks use
highly sophisticated algorithms for this, but for this assignment you will implement a fairly naive algorithm to recommend the
most likely new friend to users of a social network. In particular, you will recommend the most probable user to befriend based
upon the intersection of your common friends. In other words, the user that you will suggest to Person A is the person who
has the most friends in common with Person A, but who currently is not friends with Person A.
Five text files have been provided for you to run your program with. Each represents a social network. Three are small
test files containing a made-up set of users and their friendships (these files are net1.txt, net2.txt and net3.txt). The two are a
subset of a real Facebook dataset, which was obtained from: fhttps://snap.stanford.edu/data/egonets-Facebook.html
The format of all five files is the same:
The first line of the file is an integer representing the number of users in the given network.
The following lines are of the form: user_u user_v where user_u and user_v are the (non-negative integer) IDs of two users
who are friends.
In addition user_u is always less than user_v
For example, here is a very small file that has 5 users in the social network: 5
0 1
1 2
1 8
2 3
The above is a representation of a social network that contains 5 users.
User ID=0 is friends with User IDs = 1
User ID=1 is friends with User IDs = 0, 2, 8
User ID=2 is friends with User IDs = 1, 3
User ID=3 is friends with User IDs = 2
User ID=8 is friends with User IDs = 1
Spend time studying the above small example to understand the model. For example, notice that since friendship is a
symmetric relationship the social media networks in this assignment, if user_u is friends with user_v, that means that user_v
is also friends with user_u. Such “duplicate” friendships are not present in the file. In particular each friendship is listed once
in such way that user_u < user_v
Also note that, while you can assume that user IDs are sorted, you cannot assume that they are consecutive integers
differing by one. For example the user IDs above are: 0,1,2,3,8.
You can also assume that in each file the users are sorted from smallest to largest (in the above example you see that users
appear as: 0 1 1 2). Specifically, friendships of user_u appear before friendships of user_v if and only if user_u < user_v.
And also for each user its friends appear sorted, for example for user 1 friendship with friend 2 appears before friendship with
friend 4.
2
To complete the assignment you will have to code the following 9 functions. I strongly recommend you code the in the order
given below and do not move onto coding a function until you complete all before. The function descriptions, including what
they need to do, are given in a4_xxxxxx.py.
1. create_network(file_name) (35 points) This is the most important (and possibly the most difficult) function to solve.
The function needs to read a file and return a list of tuples representing the social network from the file. In particular the
function returns a list of tuples where each tuple has 2 elements: the first is an integer representing an ID of a user and
the second is the list of integers representing his/her friends. In the a4_xxxxxx.py I refer the list that create_network
function returns as a 2D-list for friendship network (although one can argue that is is a 3D list). In addition the
2D-list for friendship network that must create_network function returns must be sorted by the ID and a list
of friends in each tuple also must be sorted.
So for the example above, this function should return the following 2D-list for 2D-list for friendship network:
[(0, [1]), (1, [0,2,8]), (2,[1,3]), (3,[2]), (8,[1])]
More examples:
>>> net1=create_network("net1.txt")
>>> net1
[(0, [1, 2, 3]), (1, [0, 4, 6, 7, 9]), (2, [0, 3, 6, 8, 9]), (3, [0, 2, 8, 9]), (4, [1, 6, 7, 8]),
(5, [9]), (6, [1, 2, 4, 8]), (7, [1, 4, 8]), (8, [2, 3, 4, 6, 7]), (9, [1, 2, 3, 5])]
>>> net2=create_network("net2.txt")
>>> net2
[(0, [1, 2, 3, 4, 5, 6, 7, 8, 9]), (1, [0, 4, 6, 7, 9]), (2, [0, 3, 6,8, 9]), (3, [0, 2, 8, 9]), (4, [0, 1, 6, 7, 8]),
(5, [0, 9]), (6, [0, 1, 2, 4, 8]), (7, [0, 1, 4, 8]), (8, [0, 2, 3, 4, 6, 7]), (9, [0, 1, 2, 3, 5])]
>>> net3=create_network("net3.txt")
>>>
[(0, [1, 2, 3, 4, 5, 6, 7, 8, 9]), (1, [0, 4, 6, 7, 9]), (2, [0, 3, 6,8, 9]), (3, [0, 2, 8, 9]), (4, [0, 1, 6, 7, 8]),
(5, [0, 9]), (6, [0, 1, 2, 4, 8]), (7, [0, 1, 4, 8]), (8, [0, 2, 3, 4, 6, 7]), (9, [0, 1, 2, 3, 5]),
(100, [112]), (112, [100, 114]), (114, [112])]
>>> net4=create_network("big.txt")
>>> net4[500:502]
[(500, [348, 353, 354, 355, 361, 363, 368, 373, 374, 376, 378, 382, 388, 391, 392, 396, 400, 402, 404, 408, 409, 410, 412, 414, 416, 417, 421, 423, 428, 431, 438, 439, 444, 445, 450, 452, 455, 463, 465, 474, 475, 483, 484, 487, 492, 493, 497, 503, 506, 507, 513, 514, 517, 519, 520, 521, 524, 525, 527, 531, 537, 538, 542, 546, 547, 548, 553, 555, 556, 557, 560, 563, 565, 566, 580, 591, 601, 604, 614, 637, 645, 651, 683]), (501, [198, 348, 364, 393, 399, 441, 476, 564])]
2. getCommonFriends(user1, user2, network) (15 points)
>>> getCommonFriends(3,1,net1)
[0, 9]
>>> getCommonFriends(0,112,net3)
[]
>>> getCommonFriends(217,163,net4)
[0, 100, 119, 150]
3. recommend(user, network) (15 points)
Read the docstrings to understand how this function should work. Understand why the given friends are recommended
in the examples below including why no friend is recommended for 0 in net2 and 112 in net 3.
>>> recommend(6,net1)
7
>>> recommend(4,net2)
2
>>> recommend(0,net2)
>>> recommend(114, net3)
100
>>> recommend(112,net3)
>>> recommend(217,net4)
163
4. k_or_more_friends(network, k) (5 points)
>>> k_or_more_friends(net1, 5)
3
>>> k_or_more_friends(net2, 8)
1 3
>>> k_or_more_friends(net3, 12)
0
>>> k_or_more_friends(net4, 70)
33
5. maximum_num_friends(network) (5 points)
>>> maximum_num_friends(net1)
5
>>> maximum_num_friends(net2)
9
>>> maximum_num_friends(net3)
9
>>> maximum_num_friends(net4)
347
6. people_with_most_friends(network) (5 points)
>>> people_with_most_friends(net1)
[1, 2, 8]
>>> people_with_most_friends(net2)
[0]
>>> people_with_most_friends(net3)
[0]
>>> people_with_most_friends(net4)
[0]
7. average_num_friends(network) (5 points)
>>> average_num_friends(net1)
3.8
>>> average_num_friends(net2)
5.0
>>> average_num_friends(net3)
4.153846153846154
>>> average_num_friends(net4)
19.78
8. knows_everyone(network) (5 points)
>>> knows_everyone(net1)
False
>>> knows_everyone(net2)
True
>>> knows_everyone(net3)
False
>>> knows_everyone(net4)
False
9. get_uid(network) (10 points)
>>> get_uid(net1)
Enter an integer for a user ID:alsj
That was not an integer. Please try again.
Enter an integer for a user ID: twenty
That was not an integer. Please try again.
Enter an integer for a user ID:9aslj
That was not an integer. Please try again.
Enter an integer for a user ID:100000
That user ID does not exist. Try again.
Enter an integer for a user ID:4.5
4
That was not an integer. Please try again.
Enter an integer for a user ID: -10
That user ID does not exist. Try again.
Enter an integer for a user ID:-1
That user ID does not exist. Try again.
Enter an integer for a user ID:7
7
1.1 Bonus (15 points)
This assignment offers up to 15% bonus. The bonus is available for the maximum of 30-40 students. In order for a student to
have a chance to get the bonus the following needs to happen:
1. She needs to correctly solve/code create_network and getCommonFriends functions. She will know that that is the case
by waiting for the grading to be completed and seeing that she did not loose any points on these 2 functions; and
2. She needs to solve getCommonFriends(user1, user2, network) with running time
O(n1 + n2 + log n) were n is the the total number of users in the network, n1 is the number of friends of user1 and n2 is
the number of friends of user2. In other words, n1 =len(user1), n2 =len(user2) and n =len(network).
Note that on a typical network O(n1+n2+log n) is much better than O(n) since a network like Facebook has n roughly 2
billion and the average number of friends per user is 338. Thus the number of operations an O(n) solution would do, would
be in the order of a billion, roughly. While the number of operations an O(num_friends_user1 + num_friends_user2 + log n)
solution would do, would be in the order of, O(338 + 338 + 21), thousand, roughly
Thus O(n) solutions will not be accepted for the bonus.
To determine the running times of Python’s functions on lists you can use this link (although it is not quite correct as it
is amortized, which they incorrectly call average, analysis and not the worst case analysis).
https://wiki.python.org/moin/TimeComplexity
Again you cannot use sets nor dictionaries nor deque nor bisect module.
3. Finally, to obtain the bonus the student needs to come to my office hours in order to explain her faster solution (my last
office hour will be on Dec 2nd.)
 
联系我们
  • QQ:99515681
  • 邮箱:99515681@qq.com
  • 工作时间:8:00-23:00
  • 微信:codinghelp2
热点文章
程序代写更多图片

联系我们 - QQ: 99515681 微信:codinghelp2
© 2014 www.7daixie.com
程序代写网!