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lab39
nested ifs

Consider the following problem: At a bakery, you can order either donuts, or fritters:

Delicious Sugarbomb Donuts cost 65¢ each; if you order 10 or more you get a 5% discount on all your donuts.
Fatty Fritters cost 110¢ each; if you order 4 or more you get a 10% discount on all your fritters.

def test():
    print( "0 donuts:" )
    print( "Actual:  " + str(orderPrice( "donuts", 0 )) )
    print( "Desired: " + str(...) )
    print( "1 donut:" )
    print( "Actual:  " + str(orderPrice( "donuts", 1 )) )
    print( "Desired: " + str(...) )
    print( "2 donuts:" )
    print( "Actual:  " + str(orderPrice( "donuts", 2 )) )
    print( "Desired: " + str(...) )
    print( "10 donuts:" )
    print( "Actual:  " + str(orderPrice( "donuts", 10 )) )
    print( "Desired: " + str(...) )
    print( "100 donuts:" )
    print( "Actual:  " + str(orderPrice( "donuts", 100 )) )
    print( "Desired: " + str(6175) )  # 6500¢ less 5% (325¢)

    print( "0 fritters:" )
    print( "Actual:  " + str(orderPrice( "fritter", 0 )) )
    print( "Desired: " + str(...) )
    print( "1 fritter:" )
    print( "Actual:  " + str(orderPrice( "fritter", 1 )) )
    print( "Desired: " + str(...) )
    print( "2 fritters:" )
    print( "Actual:  " + str(orderPrice( "fritter", 2 )) )
    print( "Desired: " + str(...) )
    print( "4 fritters:" )
    print( "Actual:  " + str(orderPrice( "fritter", 4 )) )
    print( "Desired: " + str(...) )
    print( "100 fritters:" )
    print( "Actual:  " + str(orderPrice( "fritter", 100 )) )
    print( "Desired: " + str(...) )

We'll go over the solution in class. You can see the solution here lab39-soln.html.

YOUR TASK:

Write a function enhancePixelAt : Picture, int, int, → None, which takes in an image, an x-coordinate, and a y-coordinate, and changes the pixel according ot the following:
- If the redness is more than 220, then set the pixel to black. (Red-eye reduction?)
- Otherwise, if the average brightness ¹ is more than 200, then make the pixel 20% darker (reduce highlights)
- Otherwise, make the pixel's redness 15% more (enhance skin-tones).
Write enhance : Picture → None, which takes in a picture an enhances each pixel. (Of course, you'll want a helper-function enhanceOneRow : Picture, int → None

Use an if-else inside an if-else, to handle the three different cases. We'll spend tomorrow, finishing this up.

Note: You may adjust the exact conditions to your taste, if you think that would help the result look better. In particular, the first condition is perhaps a bit too lax, to just detect high-redness!

Note: The above description is intentionally a bit high-level — e.g. “set a pixel to black” might require three statements that we've used before.

¹ A pixel's brightness is the sum of its red,green,blue channels divided by three (to bring it back into the range [0,256)). ↩

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©2014, Ian Barland, Radford University
Last modified 2014.Apr.18 (Fri) Please mail any suggestions
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lab39 nested ifs

lab39
nested ifs