Exercise #3 Solution

This exercise is designed to get you writing functions using selection. In les called ex3.py and ex3.test, create the two functions described below. As before, your le must not use print, input or import.




GPV Calculator




Create a function called percent to gpv that takes a percentage mark (int) as input, and returns the corresponding Grade Point Value (float). GPV is calculated as follows:







Table 1: default




Percentage Mark
GPV




90-100
4.0




85-89
4.0




80-84
3.7




77-79
3.3




73-76
3.0




70-72
2.7




67-69
2.3




63-66
2.0




60-62
1.7




57-59
1.3




53-56
1.0




50-52
0.7




0-49
0.0










You can safely assume that we will not give you values outside of the given ranges for testing, but your docstring should make it clear what values are acceptable




Card Naming




Write a function called card namer that takes two single character strings, representing the value and suit of a card following the shorthand below, and returns the full name of the card. Some sneaky cheaters have been trying to slip in fake cards, like the 9 of triangles. So if the suit input isn't one of the recognized inputs the function should return 'CHEATER!'1. You may assume that value will be always be a valid input.







Input
Value




A
Ace




2 .. 9
2 .. 9




T
10




J
Jack




Q
Queen




K
King










Input
Suit




D
Diamonds




C
Clubs




H
Hearts




S
Spades
















HINT: There is an easy and a hard way to go about writing this function. If you're doing it properly, you should only need two if statements and no more than ~25 lines of code.



1
An example output of the function would be:




card_namer( Q , D ) Queen of Diamonds



card_namer( 9 , S ) 9 of Spades



card_namer( 8 , T ) CHEATER!



BONUS: Our Own str() Function




This one is a bonus. (We'll still run the auto-marker, but it won't count towards your mark)2. We've been using the str() function in class quite frequently to turn other data types into strings. However, I'd now like to build our own version, so that we can control exactly how the conversion happens.




Create a function called my str that takes an object as input3, and returns a string representation of that object. However, we don't want to use the boring old built-in representations, we're going to make our own.







If the input is a string, just return it as it is




If the object is a boolean, return "YES" (for True) or "NO" (for False) If the object is an integer:




{ If it's less than or equal to 10, return "Small Number", for 11 - 99 return "Medium Number", for anything larger return "Large Number"




If the object is a oat, return a standard string representation, but rounded to at most 2 decimal places { Try to do this with just a single call to round()




If the object is any other data type, simply return the phrase "I dunno" Some sample output from the function4:




isinstance("Hello",str)



True




isinstance(True,bool)



True




 
my_str("Hello")



Hello




my_str(False)



NO




my_str(42)



Medium Number




my_str(42.0) 42.0



my_str(3.1415926) 3.14



my_str([1, 2, 3]) I dunno






It's okay if you submit a partial solution, but make sure it doesn't have any syntax errors that would prevent your other functions from running, and also keep in mind that things like PEP-8 will be run for the whole le, so an error here is still an



error




3An object is a generic term for any piece of data regardless of type, you can use something like (obj) - str as your type contract




4Note to self. Make sure not to accidentally copy/paste any extra lines of code that you typed before testing your function. Particularly not any lines that would be very helpful in completing the bonus question.




2