CPSC120A
Fundamentals of Computer Science I

Lab 16

Chained Conditionals

Practice 1

Write the function rps_string(integer) that returns the string 'rock', 'paper', 'scissors', or 'error' depending on the value of the specified integer. If integer is 0, the function should return 'rock'. If integer is 1, the function should return 'paper'. If integer is 2, the function should return 'scissors'. If integer is not 0, 1, or 2, the function should return 'error'. Use chained conditionals to simplify the code. 







  
Practice 2



  Write the function normalize(integer) that returns the
  clamped normalization of the specified integer.
  If integer is less than 0, the function should return
  0.0.  If integer is greater than 100, the function
  should return 1.0.  If integer is in the range [0,
  100], the function should return integer / 100.0.  Use
  chained conditionals to simplify the code.




  


  

  

    
  

  





Grade Conversion



  You would think students would be used to the letter grade system.
  However, I still have students ask how their letter grade is relates
  to their numeric grade.  Let's write a program to help these
  students, applying what you just learned about conditionals.



Details



  In a file called grades.py, write a function
  called convert_grade(numeric).  This function takes an
  integer which should be greater than 0, and represents some students'
  grades.  Your function should return a string with a single
  character, either 'A', 'B', 'C', 'D', or 'F'.  Use the following
  scale for your conversions.  Do not use any logical
  operators for this exercise.




  
A
\([90, 100]\)

  
B
\([80, 90)\)

  
C
\([70, 80)\)

  
D
\([60, 70)\)

  
F
\([0, 60)\)





  Note that square brackets mean inclusive, and parenthesis means
  exclusive.




  Make sure to test your function by calling the function multiple
  times with different parameters.  Make sure your code follows the
  course's code conventions.



Test Cases



  
    

      Function Parameters
      Expected Output
    

  
  
    

      95
      A
    

    

      90
      A
    

    

      89
      B
    

    

      80
      B
    

    

      79
      C
    

    

      70
      C
    

    

      69
      D
    

    

      60
      D
    

    

      59
      F
    

  



Hint



  
  

    

      Make sure you pay attention to order.  If you chose your order
      carefully (such as starting at the F range) you can
      simplify your conditions greatly.
    

    

      Syntatically we don't care about having multiple returns in a
      function.  However, stylistically we want to limit the number of
      return statements.  For the time being, only use one return
      statement.  To do so, store what you are returning in a
      variable, that you create at the beginning of the function.
    

  






  
Challenge

  

    Most users like more levels of specification.  For example, on the
    Roanoke College campus we use the +/- system as well.  Add code to
    your function so that it can also output A+'s and D-'s.  Recall that
    there is no such thing as an F+ or F-.  
  

  

    For all levels (except for F), you get a + if the 1's place is 7
    or greater.  You get a - if the 1's place is 3 or less.
  




Leap Years




  One of the most confusing aspects of validating dates is accounting
  for the number of leap years in that period.  Every year, there is
  roughly an extra \(\frac{1}{4}\) day.  To account for
  this, almost every 4 years we add an additional day to the 
  month of Februray.  The rules for this are straight-forward, but
  the reasoning and implementation of them is sometimes confusing.




Details




  In a file called date_validation.py, write a set of test
  cases to ensure your is_leap_year(year) function
  operates under the following specification.





  A leap year occurs almost every 4 years.  All leap years are
  divisible by 4, but not all years divisible by 4 are leap years.
  A year is a leap year if it is divisible by 4, unless it is
  divisible by 100 and not divisible by 400.
  
    Your function should return True if the
  year parameter is a leap year, and False otherwise.




Sample Test Cases



  
    

      Function Parameters
      Expected Output
    

  
  
    

      1900
      False
    

    

      2000
      True
    

    

      1996
      True
    

    

      2015
      False
    

  



Hint



  
  

    
    
      
  • 
	
    
	  You can use the % (mod) operator to test
	  divisibility.  If year % 4 is 0, then year is
	  divisible by 4.
	
    
      
    • 
      
  • 
	
    
	  Dont forget that you can use your logical constructs to
	  reduce the complexity of the condition checks.
	
    
      
    • 
  






  
Challenge

  

    Another approach to testing is exhaustive enumeration.  There have
    been 2015 years since the beginning of the common era.  Write code
    that checks all of the years since 0 A.D.  Compute the total
    number of leap years in that time frame.
  




Submission


Please show your source code and run your programs for the instructor or lab assistant. Only a programs that have perfect style and flawless functionality will be accepted as complete.