Suppose we have these definitions from last week's quiz:
from collections import namedtuple
Date = namedtuple('Date', 'year month day')
where all three fields are numbers, so that November 12, 2012 would be represented as Date(2012, 11, 12).
DrivingRecord = namedtuple('DrivingRecord', 'name license age tickets')
where name is a string representing a driver's name, license is a string representing his or her driver's licence number, age is the driver's age, and tickets is a (possibly empty) list of Date objects containing the dates on which the driver has received a traffic ticket (i.e., was cited by a police officer for violating a driving law).
Complete the definition of Date_is_earlier below, consistent with its header, docstring, and assertions:
def Date_is_earlier(date1: Date, date2: Date) -> bool:
''' Return True if date1 is earlier than date2 (and False otherwise---
for a boolean function, this goes without saying; it has to return
either True or False)
'''
assert(Date_is_earlier(Date(2012, 1, 1), Date(2013, 1, 1)))
assert(Date_is_earlier(Date(2012, 1, 1), Date(2012, 2, 1)))
assert(Date_is_earlier(Date(2012, 1, 1), Date(2012, 1, 2)))
assert(Date_is_earlier(Date(2013, 1, 14), Date(2013, 2, 1)))
assert(not Date_is_earlier(Date(2013, 1, 14), Date(2013, 1, 1)))
assert(not Date_is_earlier(Date(2013, 5, 1), Date(2013, 1, 1)))
assert(not Date_is_earlier(Date(2013, 5, 14), Date(2013, 1, 1)))
assert(not Date_is_earlier(Date(2013, 5, 1), Date(2013, 1, 14)))
assert(not Date_is_earlier(Date(2012, 1, 1), Date(2012, 1, 1)))
assert(not Date_is_earlier(Date(2013, 1, 2), Date(2013, 1, 1)))
assert(not Date_is_earlier(Date(2012, 2, 1), Date(2012, 1, 1)))
assert(not Date_is_earlier(Date(2013, 1, 1), Date(2012, 1, 1)))
assert(not Date_is_earlier(Date(2013, 1, 1), Date(2012, 2, 1)))
if date1.year < date2.year:
return True
elif date1.year > date2.year:
return False
elif date1.month < date2.month:
return True
elif date1.month > date2.month:
return False
elif date1.day < date2.day:
return True
else:
return False
One way to approach this problem is to look at the assertions. There's no guarantee that every set of assertions on an exam
will be comprehensive, but this one is: It lays out the various cases to check: Are the years different (d1 < d2, or d1 > d2 actually)? If the years are equal, are the months different (d1 < d2 or d1 > d2)? If not, are the
days different (d1 < d2)?
For this problem, assume that you have the following function already defined; you do not have to define it:
def Date_is_weekend(d: Date) -> bool:
''' Return True if d is a Saturday or Sunday '''
Complete the definitions below of the functions total_tickets, total_weekend_tickets, and weekend_ticket_percentage.
def total_tickets(DRL: 'list of DrivingRecord') -> int:
''' Return the total number of tickets issued to all drivers in DRL
'''
def total_weekend_tickets(DRL: 'list of DrivingRecord') -> int:
''' Return the total number of tickets issued on Saturday or Sunday.
You may write a second function (a "helper function") to break this task down.
'''
def weekend_ticket_percentage(DRL: 'list of DrivingRecord') -> float:
''' Return the percentage of all tickets issued that were issued
on a Saturday or Sunday (value from 0 to 100)
'''
Of course you need to call the previously-defined functions where appropriate;
it's never full credit to duplicate code.
def total_tickets(DRL: 'list of DrivingRecord') -> int:
''' Return the total number of tickets issued to all drivers in DRL
'''
total = 0
for dr in DRL:
total += len(dr.tickets)
return total
def total_weekend_tickets(DRL: 'list of DrivingRecord') -> int:
''' Return the total number of tickets issued on Saturday or Sunday.
You may write a second function (a "helper function") to break this task down.
'''
total = 0
for dr in DRL:
total += total_weekend_tickets_on_ticketlist(dr.tickets)
return total
# Alternative (without a helper function, using a nested loop):
# total = 0
# for dr in DRL:
# for d in dr:
# if Date_is_weekend(d):
# total += 1
# return total
def total_weekend_tickets_on_ticketlist(ticketlist: 'list of Date') -> int:
''' Take a list of Dates (when tickets were issued) and count the
number of tickets that were issued on Saturday or Sunday
'''
total = 0
for d in ticketlist:
if Date_is_weekend(d):
total += 1
return total
def weekend_ticket_percentage(DRL: 'list of DrivingRecord') -> float:
''' Return the percentage of all tickets issued that were issued
on a Saturday or Sunday (value from 0 to 100)
'''
return total_weekend_tickets(DRL) / total_tickets(DRL) * 100
# It would be better coding practice to check that total_tickets
# returns at least 1, since you can't divide by zero.
# Also, note that to get a percentage you need to multiply by 100.
One aspect of this question is being able to USE a function
whose header and docstring are supplied, even if you don't
have the body of the function. This is a common programmer's
experience---any time you use help() or look up the functions
and methods in a library, you do this.
Suppose we have a file of driving records as shown below:
John Jones 111222333 24 12/24/11,1/31/12,6/30/12
Jane Johnson 222333444 25
Joe Jenkins 333444555 18 4/5/12
Jill Jefferies 444555666 55 2/24/01,10/18/05
The four fields are separated by tabs; the list of ticket dates is separated by commas; each date is in mm/dd/yy format.
The following code creates a list of DrivingRecords from a file like the one above.
def mmddyy_to_Date(mmddyy: str) -> Date:
''' Return Date from mm/dd/yy
'''
parts = mmddyy.split('/')
return Date(int(parts[0]), int(parts[1]), 2000+int(parts[2]))
## ALTERNATIVE 1
infile = open('records.txt', 'r')
inputlist = infile._______________()
DRL = [ ]
for dr in inputlist:
fields = dr.split('\t')
if len(fields) == 3:
ticketlist = [ ]
else:
ticketlist = fields[3].strip().split(',')
Datelist = []
for d in ticketlist:
Datelist.append(mmddyy_to_Date(d))
record = DrivingRecord(fields[0], fields[1], int(fields[2]), Datelist)
DRL.append(record)
print(DRL)
infile.close()
## ALTERNATIVE 2
infile = open('records.txt', 'r')
DRL = [ ]
for _______________ in _______________:
fields = line.split('\t')
if len(fields) == 3:
ticketlist = [ ]
else:
ticketlist = fields[3].strip().split(',')
Datelist = []
for d in ticketlist:
Datelist.append(mmddyy_to_Date(d))
record = DrivingRecord(fields[0], fields[1], int(fields[2]), Datelist)
DRL.append(record)
print(DRL)
infile.close()
## ALTERNATIVE 3
infile = open('records.txt', 'r')
inputstring = infile._______________
inputlist = inputstring.split('\n')
DRL = [ ]
for dr in inputlist:
fields = dr.split('\t')
if len(fields) == 3:
ticketlist = [ ]
else:
ticketlist = fields[3].strip().split(',')
Datelist = []
for d in ticketlist:
Datelist.append(mmddyy_to_Date(d))
record = DrivingRecord(fields[0], fields[1], int(fields[2]), Datelist)
DRL.append(record)
print(DRL)
infile.close()
There are five different ways to read text files in Python:
Match each of the ways listed above with one of the following statements: