CS 190C LAB 3: Friday, January 30, 2009

def main():
    f = open('actor2.txt', 'r')
    previous_year = ''
    for line in f:
        nomination = line.split(',')
        if nomination[0] != previous_year:
            print nomination[1]
        previous_year = nomination[0]
    f.close()
 
main()

If something is mutable, it means that it can be changed. In Python, lists are mutable, but strings are not. Example:

>>> x = 'hello'
>>> x
'hello'
>>> x[0] = 'j'
Traceback (most recent call last):
  File "<pyshell#22>", line 1, in <module>
    x[0] = 'j'
TypeError: 'str' object does not support item assignment

If we convert x into a list of characters instead, we can indeed change the h to a j:

>>> x = list(x)
>>> x
['h', 'e', 'l', 'l', 'o']
>>> x[0] = 'j'
>>> x
['j', 'e', 'l', 'l', 'o']

The caveat is now our string is not a string. To convert it back:

>>> x = ''.join(x)
>>> x
'jello'

raw_input(), like input(), can be used to retrieve input. However, raw_input() behaves differently:

• raw_input() always returns a string
• the input to raw_input() does not have to be a legal Python expression
• raw_input() is often used to obtain text input from a user. If you use input(), in order to get text input, you must surround your text with quotes.

>>> x = raw_input('input something: ')
input something: test
>>> x
'test'
>>> x = input('input something: ')
input something: 'test'
>>> x
'test'
>>> x = raw_input('input something: ')
input something: 0.5
>>> x
'0.5'
>>> x = input('input something: ')
input something: 0.5
>>> x
0.5

Case-sensitive string comparison can be done in the same way you compare numbers:

>>> 'bob' == 'bob'
True
>>> 'bob' == 'BOB'
False

For today's problem, however, you need to deal with strings that may not be in the same case. If the user inputs “bob”, you still want it to be basically the same as “BOB”. One easy way is to compare the lowercase version of these strings:

>>> x = 'bob'
>>> y = 'bob'
>>> z = 'BOB'
>>> x.lower() == y.lower()
True
>>> x.lower() == z.lower()
True

Download one of the files to use as your database:

actor2.txt actress2.txt

1. Search your file of nominations and print out the nominations or awards that the actor received. You should clarify whether or not it is a nomination or an award. The first nomination of each year is the award for that year, since it isn't explicitly specified in the file. The search should not be case sensitive. For example, if the user types in “tom hanks”, it should still match nominations for “Tom Hanks”. Your output may look like this:

   Enter the actor: tom hanks
   Tom Hanks was nominated for an Oscar in 1988 for Big as Josh Baskin
   Tom Hanks won an Oscar in 1993 for Philadelphia as Andrew Beckett
   Tom Hanks won an Oscar in 1994 for Forrest Gump as Forrest Gump
   Tom Hanks was nominated for an Oscar in 1998 for Saving Private Ryan as Captain John H. Miller
   Tom Hanks was nominated for an Oscar in 2000 for Cast Away as Chuck Noland

2. Lastly, since there is no reason why you need the entire list of Oscar nominees at once, you should process each line one at a time, rather than loading all of the entries before doing a search.

def main():
    f = open('actor2.txt', 'r')
    prev_year = 0
    actor = raw_input('Enter the actor: ')
    for line in f:
        nomination = line.split(',')
        nomination[0] = int(nomination[0])
        if nomination[1].lower() == actor.lower():
            if prev_year != nomination[0]:
                print nomination[1], 'won an Oscar in', nomination[0], 'for', nomination[2]
            else:
                print nomination[1], 'was nominated for an Oscar in', nomination[0], 'for', nomination[2]
        if nomination[0] != prev_year:
            prev_year = nomination[0]
 
    f.close()
main()