'''lists.py

   Jeff Ondich, 11 September 2009

   This sample program will introduce you to Python lists.
   Read the code, figure out what it does, and try to answer
   any questions in the comments below.
'''

# Creating and printing a list
# -- How would you print just the third item in this list?  (Go back
#       to strings1.py for a hint.)
# -- What happens if you try to print the 5th item in this list?

firstList = [5, 'tapir', 32.4, 'something']
print firstList
print

# Concatenating lists
# -- What does using the + operator between lists do?
# -- Does concatenating lists modify the original lists?

secondList = ['dog', 'cat', 'llama']
thirdList = firstList + secondList
print 'First list:', firstList
print 'Second list:', secondList
print 'Third list:', thirdList
print

# Iterating over a list's contents
#  Just as with the strings in strings2.py, there are two main ways
#  to iterate over the elements in a list.
# -- What happens if you change "item" to some other word everywher
#    "item" appears?  Do the loops still work?
# -- What happens if you change the word "in" to something else?
#    Does the first loop still work?
# -- Does TextWrangler give you any hints about which words you get
#    to change and which ones you don't?

print 'Iterating over a list'
for item in firstList:
    print item
print

print 'Iterating again, but in a different way'
k = 0
while k < len(firstList):
    print firstList[k]
    k = k + 1
print

# A couple list operations.  Figure out what they're doing, and how
# append and extend differ.

theList = [4, 5, 6]
print 'Before append:', theList
theList.append(7)
print 'After append:', theList
print

theList = [4, 5, 6]
otherList = [7, 8]
print 'Before extend:', theList
theList.extend(otherList)
print 'After extend:', theList
print

theList = [4, 5, 6]
otherList = [7, 8]
print 'Before append:', theList
theList.append(otherList)
print 'After append:', theList
print


# Some questions for your amusement.
# -- Can a list contain a list as one of its elements?
# -- Does slicing work with lists?