[Courses] [python] Lesson 3: Fun with Strings and Lists

[Svenja S.]

================== Homework ======================

1. How would you count the number of words in a single string?
   Assume words are separated by spaces ... don't worry about
   things like newlines, commas or hyphens.

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input_str = raw_input("Enter some words...")
input_list = input_str.split(" ")
print "You entered" , len(input_list) , "words."

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2. What does an index of [-1], or another negative number mean in a
   list or string? Take a guess, then try it and see if you were right.

My guess would have been that it referred to the list itself or something, but it seems like it refers to the last element of the list. 

3. Who is Guido van Rossum and why am I using him as an example?

Mh, no clue, and googling kind of feels like cheating.

4. Rewrite the exercise from lesson 2, the one where
   you printed "one", "two", "three", "four", "five",
   using a list instead of a series of if-elif.
   (A few people already posted solutions that worked that way
   in their lesson 2 answers. If you already did this for lesson 2, no
   need to do it again. If you read other people's, it's still worth
   writing it yourself now without going back and looking.)


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numbers = ["one", "two", "three", "four", "five"]
for n in numbers:
  print n

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 5. This one's a little harder, but give it a try if you have time.
   Plot a histogram graph from a list of numbers, with each number in
   the list on its own line.

   For instance, if you start with numbers like this:
vals = [ 0, 2, 4, 8, 16, 18, 17, 14, 9, 7, 4, 2, 1 ]
   you might plot something like this:

**
****
********
****************
******************
*****************
**************
*********
*******
****
**
*
    where the first line has no stars, the second has two, then 4, etc.
    Hint: you'll need two loops, one inside the other.


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vals = [ 0, 2, 4, 8, 16, 18, 17, 14, 9, 7, 4, 2, 1 ] 

for v in vals:
  cur_str = ""
  for i in range(0,v):
    cur_str += "*" 
  print cur_str

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