SI206  Homework #6-Regular Expressions Solution

In this homework, you have been given the book Alice in Wonderland by Lewis Carroll in a text file called "alice_in_wonderland.txt". However, the Mad Hatter, a fictional character in the book, has corrupted the file and added some clues to the text file. Your job is to use regular expressions to find this information as times, URLs, dates, and words contained in underscores.

To do so, you will complete the following functions in wonderland.py:

1. find_times (string_list)
This function finds and returns all the hidden times which match the following conditions:
a. It should start with 1 – 12.
b. It should be followed by a colon (:)
c. It should be followed by two digits between 00 – 59.
d. It should end with am or pm (with one space between the numbers and the letters)

These are examples of valid times:

11:00 pm
12:25 am
5:00 pm

2. find_urls (string_list)
This function finds and returns all the hidden urls which match the following conditions:
a. The URL should start with http:// or https://.
b. Followed by a www.
c. Followed by any characters except for whitespace.
d. It should contain a .com or .org.
e. Followed by any characters except for whitespace.

These are examples of valid URLs:

http://www.gutenberg.org/1/11/org https://www.pythex.com
https://www.youtube.com/watch?v=msvOUUgv6m8








3. find_dates (string_list)

mm/dd/yyyy mm/dd/yy mm-dd-yyyy mm-dd-yy mm.dd.yyyy mm.dd.yy
dd.mm.yyyy (day and month can be switched like this too)



4. find_underscore(string_list)
The function should find and return a list of all the words contained by an underscore. Return only words that do not have punctuation.

_very_
_this_

Example of what not to return; _very!_

5. Make at least 3 test cases for find_time , find_urls , find_dates , and find_underscore .










Count table
To aid you in knowing when your functions are correctly implemented or not, here are the number of items that SHOULD be returned when you run your functions on the file
‘alice_in_wonderland.txt’. To run your functions, you will first have to use the provided function read_file to convert the contents of ‘alice_in_wonderland.txt’ into a list of strings. Note: your functions should return a list of items, not the number of items (except for the extra credit function). This table is for you to verify that you are returning the right list (e.g., maybe you can check the length of the list you return):

Data type Number of appearances in the text
Times 5
URLs 5
Dates 7
Underscores 177
Extra Credit: Count A

Count B 3850

1099


Grading Rubric (60 points)
This rubric does not show all the ways you can lose points.
6 points for creating tests for find_time (2 points per test case, up to a max of 6 points)
9 points for correctly implementing find_time
6 points for creating tests for find_urls (2 points per test case, up to a max of 6 points)
9 points for correctly implementing find_urls
6 points for creating tests for find_dates (2 points per test case, up to a max of 6 points)
9 points for correctly implementing find_dates
6 points for creating tests for find_underscore (2 points per test case, up to a max of 6 points) 9 points for correctly implementing find_underscore

Extra Credit (3 points):

Write a function count_char(string_list, char) to return a count of the number of times a specified character appears in a file. It should match the character when it starts or ends a word (It should not match any characters in the middle of a word). For example, if called with “a” it should match “Apple”, “pasta”, "away", "Along", but not “farewell”. Make sure to account for punctuation (e.g ‘,’ ‘?’) in your regular expression. You MUST use a regular expression to earn credit for this part.

(We will not be checking if you make tests for the extra credit, but feel free to write your own tests if it will help you complete this problem!)


Submission: