CSc 120: Street Hints

1. Think about a function print_street_at_height(elements, height) that produces a single line of output: the street at the specified height. For example, again consider this street, with heights shown in a column on the right:

                                     height
   +-------------------------------+
   |                               |   7
   |                   xxxxx       |   6
   |                   xxxxx       |   5
   |         *         xxxxx       |   4
   |        ***        xxxxx       |   3
   |       *****       xxxxx       |   2
   |         |         xxxxx       |   1
   |         |         xxxxx  ~  ~ |   0
   +-------------------------------+
   

   The call print_street_at_height(..., 0) would print this line:

   |         |         xxxxx  ~  ~ |
   

   The call print_street_at_height(..., 2) would print this line:

   |       *****       xxxxx       |
   

   Thus, calling print_street_at_height with a series of descending heights would produce the rendering, excluding the top and bottom borders.

2. Think about having Building, Park, and EmptyLot classes. Give each class an at_height method that returns a string that is the text for that element at the specified height. Example: (blank lines added for clarity)

   >>> b = Building(3,4,"x")  # NOTE: this is not the same building that's shown above!
   
   >>> b.at_height(0)
   'xxx'
   
   >>> b.at_height(4)
   '   '
   

   Next, consider this:

   >>> s = [EmptyLot(5,"_"), Building(3,4,"x"), Park(7,"*")]
   
   >>> h = 0
   >>> s[0].at_height(h) + s[1].at_height(h) + s[2].at_height(h)
   '     xxx   |   '
   
   >>> h = 2
   >>> s[0].at_height(h) + s[1].at_height(h) + s[2].at_height(h)
   '     xxx ***** '
   

3. Combining the ideas of (1) and (2) leads to this:

   >>> s = [EmptyLot(5,"_"), Building(3,4,"x"), Park(7,"*")]
   >>> print_street_at_height(s, 5)
                  
   >>> print_street_at_height(s, 4)
              *   
   >>> print_street_at_height(s, 3)
        xxx  ***  
   >>> print_street_at_height(s, 2)
        xxx ***** 
   >>> print_street_at_height(s, 1)
        xxx   |   
   >>> print_street_at_height(s, 0)
        xxx   |   
   

   Note: The version of print_street_at_height used above output a newline after the text to make for a clear example but in practice you may find that having print_street_at_height output a newline creates problems.