Description
In this assignment, you will create a Python program (hw2.py) that processes times.
All times in the program are represented by (hour, minute, AM/PM) tuples. Hours and minutes are
represented using integers and AM/PM is represented by strings (either AM or PM). Example:
The time 4:12 PM is represented by the tuple (4, 12, “PM”). You must create the following
functions and top-level functionality:
createTimeList
Parameters: Name of the input file (string)
Returns: A list of time tuples. Each time tuple has three elements in this order: (hours – integer,
minutes – integer, AM / PM – string). The function is also capable of throwing exceptions (see
description).
Description: Reads a text file (the name of the file is stored in the parameter filename) consisting
of times and returns a list of time tuples. Each line in the file represents a single time and the order
of the items in the list must match the order in the file.
A valid line representing a time consists of these three fields, in this order, separated by spaces:
1. hour (integer from 1-12)
2. minute (integer from 0-59, can have leading zeros such as 09)
3. AM / PM (string, either AM or PM in uppercase letters only)
The line is invalid if any of the following are true:
• incorrect number of fields
• a field has the wrong type
• a field has the correct type but an unacceptable value (such as 0 for hours)
This function must also perform error checking by throwing the following programmer-defined
exceptions:
• EmptyFile: The file is empty.
• ImproperTime: This exception is raised if any of the times are invalid.
The function also can throw the system-defined exception FileNotFoundError if the file does
not exist. This exception is automatically thrown by open so no additional work by the
programmer is necessary. Other exceptions may be possible but they are not relevant for this
assignment.
IMPORTANT: This function only throws the exceptions. It does not catch them. The exceptions
are caught in the top-level functionality.
2
timeCompareGen
Parameters: List of time tuples returned from createTimeList, and a single “target” time tuple
Description: This function is a generator function that will yield for each time tuple in the list of
time tuples, a tuple that indicates how far in the future it is from target. The yielded tuples will
contain two integers in this order: (hours, minutes)
Example usage – assume the target is: (4, 12, “PM”)
Time Tuple Difference
(4, 13, “PM”) (0, 1) 1 minute in the future
(6, 20, “PM”) (2, 8) 2 hours and 8 minutes in the future
(4, 12, “AM”) (12, 0) 12 hours in the future
(4, 11, “PM”) (23, 59) 23 hours and 59 minutes in the future
In addition to these functions, you must do the following steps to create a simple test driver. This
code should reside outside the functions:
1. Get the name of an input file from the command line (using sys.argv). WARNING: Do not
prompt the user for a file name.
2. Call createTimeList with the input from the command line and storing its result into
timeList.
3. Create exception handlers for the EmptyFile, ImproperTime, and
FileNotFoundError exceptions. Each exception must have their own exception
handler that prints an error message specific to the type of exception and exits the program.
4. Use a single list comprehension over timeList that displays each time as a string in the
format “4:09 PM”. The minutes field must be exactly two digits and there is a single space
before AM or PM. Print this list.
5. Using a single call to max, find the time that occurs latest in the day. Print the result.
− To accomplish this, you will need to set the parameters appropriately – see the
documentation for max.
− You can write other code and functions to assist but you must use max (only once) to
determine the latest time.
6. Using a single call to sorted, print the times in ascending order (earliest in the day to latest
in the day).
− To accomplish this, you will need to set the parameters appropriately – see the
documentation for sorted.
− You can write other code and functions to assist but you must use sorted (only once) to
sort the list.
7. Create a variable target that is the first entry in timeList.
8. Use a single list comprehension that creates a list with the yielded values by calling
timeCompareGen with timeList and target. Print this list.
Notes:
• You may NOT use the datetime (or similar) library for this assignment.
• You may create other functions beyond what is listed here.
3
Sample Input File and Output
A sample input file is provided on cs1 at:
/home/fac/bdiazcosta/cpsc3400/hw2/sample.txt
Here are the contents of that file:
4 12 PM
8 23 PM
4 03 AM
1 34 AM
12 48 PM
4 13 AM
11 09 AM
3 12 PM
4 10 PM
If your program is working correctly, it should have the following output:
[‘4:12 PM’, ‘8:23 PM’, ‘4:03 AM’, ‘1:34 AM’, ’12:48 PM’, ‘4:13 AM’,
’11:09 AM’, ‘3:12 PM’, ‘4:10 PM’]
(8, 23, ‘PM’)
[(1, 34, ‘AM’), (4, 3, ‘AM’), (4, 13, ‘AM’), (11, 9, ‘AM’), (12, 48,
‘PM’), (3, 12, ‘PM’), (4, 10, ‘PM’), (4, 12, ‘PM’), (8, 23, ‘PM’)]
[(0, 0), (4, 11), (11, 51), (9, 22), (20, 36), (12, 1), (18, 57), (23,
0), (23, 58)]
IMPORTANT! Do not assume that testing is complete if your program produces the correct output
for this provided input file. During grading, your assignment will be tested with other input files.
Grading
Grading will be based on the following rubric:
createTimeList (correct functionality, no exceptions) 9 points
• All tests pass (no penalty)
• One test fails -4
• Two tests fail -6
• Three or more tests fail -9
Additional restrictions:
• Does not return a list of tuples -6
• Tuples do not contain the proper types -4
4
Exception handling (createTimeList and Step 3) 12 points
• Nine exceptional test cases -1 for each failing test
• Does not print error messages specific to that type of exception -2
• Does not exit the program after an exception -1
Additional restrictions:
• Does not implement exception handling as directed -4
• Does not use exception handling mechanism to catch errors -10
timeCompareGen (correct functionality) 9 points
• All tests pass (no penalty)
• One test fails -4
• Two tests fail -6
• Three or more tests fail -9
Additional restrictions:
• Not implemented as a generator function -6
• Does not yield tuples -5
• Yielded tuples do not contain the proper types -3
List comprehension – list of time strings (Step 4) 5 points
• All tests pass (no penalty)
• One test fails -3
• Two or more tests fail -5
Additional restrictions:
• Minor formatting issues -1 (per issue)
• Not putting a leading zero for minutes -2
• Not implemented using a single list comprehension -4
• Times are not converted to strings -5
Latest time using single call to max (Step 5) 5 points
• All tests pass (no penalty)
• One test fails -3
• Two or more tests fail -5
Additional restrictions:
• Not implemented using a single call to max -4
Sorting times in ascending order using single call to sorted (Step 6) 5 points
• All tests pass (no penalty)
• One test fails -3
• Two or more tests fail -5
Additional restrictions:
• Not implemented using a single call to sorted -4
5
List comprehension – list of time difference tuples (Step 8) 5 points
• All tests pass (no penalty)
• One test fails -3
• Two or more tests fail -5
Additional restrictions:
• Not implemented using a single list comprehension -4
In addition, programs may lose additional points as follows:
• Up to 5 points may be deducted if the program is very unreadable.
• Up to 40 points may be deducted if your program uses the datetime (or similar) library for
this assignment.
• 6 point deduction if the file name is not obtained from the command line for part 1.
• Programs that contain syntax errors will receive a zero.
Submitting your Assignment
On cs1, run the following script in the directory with your program:
/home/fac/bdiazacosta/submit/cpsc3400/hw2_submit
This will copy the files hw2.py to a directory that can be accessed by the instructor. Please be
sure to keep the same file names or the submission program will not work. Only the last assignment
submitted before the due date and time will be graded. Late submissions are not accepted and
result in a zero.
