1. years_dictionary2.py
2. years_dictionary.py

# Given a file of the form <firstname> <year>
# creates a mapping between the first names and class
# by CSCI 111

FILENAME="data/roster.dat"

# open the file for reading
yearsFile = open(FILENAME, "r")

classYearToCount = {}

for line in yearsFile:
    firstNameAndClass = line.split()
    className = firstNameAndClass[1]
    if className in classYearToCount:
        classYearToCount[className] += 1
    else:
        classYearToCount[className] = 1
    
yearsFile.close()

for className in classYearToCount:
    print(className, classYearToCount[className])
    

# Given a file of the form <firstname> <class>
# creates a mapping between the first names and class
# by CSCI 111

FILENAME="data/roster.dat"

# open the file for reading
yearsFile = open(FILENAME, "r")

firstNameToClass = {}

for line in yearsFile:
    firstNameAndClass = line.split()
    firstName = firstNameAndClass[0]
    className = firstNameAndClass[1]
    firstNameToClass[firstName] = className

yearsFile.close()

for firstName in sorted(firstNameToClass):
    print(firstName, firstNameToClass[firstName])
    
print()
print("Which students would you like to learn about?")
print("Press enter to exit.")
    
whichName = input("For which student would you like to know their class year? ")

while whichName != "":
    print( whichName, "is in the", firstNameToClass[whichName], "class")
    whichName = input("For which student would you like to know their class year? ")

print("Thank you!  Come again!")