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I need help figuring out this code for part 2. I'm using python language, I'm given the function
def enrollments(courses):
CSE 101: Introduction to Computers – Section 2 (MW 2:30-3:50 pm)
Stony Brook University
Lab #9
Spring 2017
Assignment Due: April 14, 2017 by 11:59 pm Assignment Objective
This lab will give you some hands-on practice writing regular expressions to identify strings that match certain
patterns. Getting Started
For the labs and homework assignments in this course you will be writing functions that solve computational
problems. To help you get started on each assignment, we will give you on Piazza a “bare bones” file with a name
like lab9.py. These files will contain function stubs and a few tests you can try out to see if your code seems
to be correct. Stubs are functions that have no bodies (or have very minimal bodies). You will fill in the bodies of
these functions for the assignments. Do not, under any circumstance, change the names of the functions or their
parameter lists. The automated grading system will be looking for exactly those functions provided in lab9.py.
Please note that the test cases we provide you in the bare bones files will not necessarily be the same ones we use
during grading! Directions
• Solve the following problems to the best of your ability.
• At the top of the lab9.py file, include the following information in comments, with each item on a
separate line:
◦ your first and last name as they appear in Blackboard
◦ your Stony Brook ID #
◦ the course number (CSE 101)
◦ the assignment name and number (Lab #9)
• Your functions must be named as indicated below. Submissions that have the wrong function names can’t
be graded by our automated grading system.
• Upload your .py file to Blackboard by the indicated due date and time. Late work will not be accepted for
grading. Work is late if it is submitted after the due date and time.
• Programs that crash will likely receive a grade of zero, so make sure you thoroughly test your work before
submitting it. CSE 101 – Spring 2017 Lab #9 Page 1 Preliminaries
For this lab you will be working with regular expressions in Python. Various functions for working with regular
expressions are available in the re module. Fortunately, Python makes it pretty easy to see if a string matches a
particular pattern.
At the top of the file we must import the re module:
import re
Then we can use the search() function to test whether a string matches a pattern. In the example below, the
regular expression has been saved in a string called pattern for convenience:
phone = ’123-456-7890’
pattern = r’ˆ\d{3}-\d{3}-\d{4}$’
if re.search(pattern, phone):
print(’The string matches the pattern.’)
else:
print(’The string does not match the pattern.’)
The r that precedes the pattern string is not a typo. Rather, the r indicates that the string is a “raw” string. In
a raw string, as opposed to a “normal” string, any backslash character is interpreted as simply a backslash, as
opposed to defining an escape sequence like \n or \t. Make sure you use raw strings in your Python code when
defining regular expressions.
The ˆ and $ at the beginning and end of the regular expression indicate that the entire string must match the regular
expression, and not just part of the string. Make sure you include these symbols in your regular expressions too! Part I: Categorizing Product Labels (3 points)
Write a function category counts() that takes a single argument consisting of a list of product labels given
as strings and returns a list of four integer counts representing how many products fall into each of four categories:
• Category 1: the labels starts with the letters PQ, followed by a 5-digit number (00000 through 99999), and
ending with either an uppercase or lowercase letter X
• Category 2: the labels starts with the letters RFT, followed by any combination of 7 uppercase letters and
digits, and always ending with one additional digit
• Category 3: the labels starts with the letter A, followed by 7-10 uppercase letters, followed by 3-7 digits
• Category 4: the label does not match any of the above patterns
Examples: CSE 101 – Spring 2017 Lab #9 Page 2 Function Call
category counts([’PQ92819x’, ’TKSNC82J4A’, ’AJEIZMFWEL271827’,
’RFTJ9WZMS28’, ’CIW92KJSD’])
category counts([’PQ38400X’, ’pq38323X’, ’RFT8291912’,
’AJSKWJS83928’])
category counts([’PQ99999XX’, ’RFT00000009’, ’RRFTKMZSDDS4’,
’CSE101WOWZA’, ’RFTK9DMG828’, ’BAWDKMJDW8291242’, ’PQ12341X’]) Return Value
[1, 1, 1, 2]
[1, 0, 0, 3]
[1, 2, 0, 4] Part II: Calculating Enrollments (3 points)
Write a function enrollments() that takes a list of strings representing course IDs (e.g., “CSE 220”) and
returns a count of how many strings define valid courses. Courses should be expressed as a three-letter subject in
mixed uppercase/lowercase letters, followed by an optional space, followed by a three-digit number. So, ideally,
each course is given in a form similar to "CSE 101" or "Phy 132". One obstacle to solving this problem is
that sometimes extra characters – specifically, combinations of periods, dashes and commas – are inadvertently
inserted in between letters. In such cases we still consider the course IDs to be valid.
Examples:
Function Call
enrollments([CSE 101’, ’AMS 310’, ’PHY 132’, ’Wrt 102’])
enrollments([’CSE114’, ’ECO330’, ’CHNN 101’, ’Ams 261’,
’MAT
200’, ’WRT101’, ’frn1012’, ’che 299’])
enrollments([’C-S-E 114’, ’C.S..E215’, ’AMS-211’,
’B,,,I.-O 255’, ’-ECO 102’]) Return Value
4
5
3 Part III: Identifying Credit Cards (3 points)
Write a function credit card() that takes an integer representing a credit card number and returns the brand
of the credit card. The returned brand is given in all uppercase letters. If the card does not match any brand,
the function returns None. The table below gives the details about the credit card number formats for several
companies:
Brand
ALPHA
BETA
GAMMA
OMEGA # of Digits
16
16
16-19 (range of possible lengths)
14 Allowable Starting Digits
4026, 417500, 4405
500-549 (range of values)
62
300-305 Examples: CSE 101 – Spring 2017 Lab #9 Page 3 Function Call
credit card(4175007282312321)
credit card(5025007282312321)
credit card(62250072875454563)
credit card(30428763928172)
credit card(417500728231987)
credit card(50550072823127458)
credit card(62250072875441254563)
credit card(30628763928172) Return Value
’ALPHA’
’BETA’
’GAMMA’
’OMEGA’
None
None
None
None Note that the quotation marks displayed in the examples are there to emphasize that the return values are strings.
You should not add quotation marks to your return values. How to Submit Your Work for Grading
To submit your .py file for grading:
1. Login to http://blackboard.stonybrook.edu and locate the course account for CSE 101.
2. Click on “Assignments” in the left-hand menu and find the link for this lab assignment.
3. Click on the link for this lab assignment.
4. Click the “Browse My Computer” button and locate the .py file you wish to submit. You should be
submitting only one file!
5. Click the “Submit” button to submit your work for grading. Oops, I messed up and I need to resubmit a file!
No worries! Just follow the above directions again. We will grade only your last submission. CSE 101 – Spring 2017 Lab #9 Page 4