Contents

  1. ascii_dictionary.py
  2. years_dictionary2.py
  3. years_dictionary.py

ascii_dictionary.py 1/3

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# Demonstrate use of dictionary, using ASCII values
#

# create an empty dictionary
ascii= {}

x = ord('a')

while x <= ord('z'):
    # add mapping to dictionary of chr(x) --> x (ordinal value)
    ascii[chr(x)] = x
    x+=1

print ascii

years_dictionary2.py 2/3

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# Given a file of the form <lastname> <year>
# keep track of the number of students in each year.
# by CSCI 111, 03.14.2011

FILENAME="data/years.dat"

yearFile = file(FILENAME, "r")

yearToNumberOfStudents = {}

for line in yearFile:
    data = line.split()
    year = data[1]
    if year in yearToNumberOfStudents : # is year a key?
        yearToNumberOfStudents[year] += 1
    else:
        yearToNumberOfStudents[year] = 1
        
yearFile.close()

years = yearToNumberOfStudents.keys()
years.sort()

for year in years:
    print year, yearToNumberOfStudents.get(year)    


years_dictionary.py 3/3

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# Given a file of the form <lastname> <year>
# creates a mapping between the last names and years
# by CSCI 111, 03.14.2011

FILENAME="data/years.dat"

yearFile = file(FILENAME, "r")

lastnameToYear = {}

for line in yearFile:
    data = line.split()
    lastname = data[0]
    year = data[1]
    lastnameToYear[lastname] = year
    
yearFile.close()

print lastnameToYear

lastNames = lastnameToYear.keys()
lastNames.sort()

for name in lastNames:
    print name, lastnameToYear.get(name)    


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