Comments on: Python Challenge level 14: “walk around”

By: Dirk

Dirk — Sat, 14 Apr 2012 18:47:30 +0000

Here is the dumb way to do it.
It took me a bit longer than five minutes.

import Image im = Image.open("wire.png") print "Image info:",im.format, im.size, im.mode out = Image.new(im.mode, (100,100))


x,y,steps,d = 0,0,0,0

maxsteps = 100

directions=[(1,0), (0,1), (-1,0), (0,-1)]

dx, dy = directions[d]

for i in range(0, 100*100):

    out.putpixel((x,y),im.getpixel((i,0)))
    steps += 1

    if steps == maxsteps:

        # change direction

        d = (d + 1 if d != 3 else 0)

        dx, dy = directions[d]

        steps = 0

        if d % 2 == 0:

            # make one step less when changing direction

            # from right to down OR from left to up

            maxsteps -= 1
    # calculate next coordinates

    x  = x + dx

    y  = y + dy

out.save('14.jpg') out.show()

By: Sumod

Sumod — Wed, 10 Aug 2011 07:27:47 +0000

I got to bit.html and then got the message – ‘you took the wrong curve’. So I must have done the wrapping around incorrectly.

Not clear to me why we are using 200 as the limit. Can you please explain?

By: Kevin

Kevin — Wed, 01 Jun 2011 14:37:31 +0000

The red pixels threw me off for a while. If you simply stack the rows vertically they spell the word “bit” which takes you to a page that says “you took the wrong curve. Spent a long time after that trying to line up the red pixels another way :)

By: Marcus

Marcus — Sat, 06 Oct 2007 19:43:26 +0000

Taher,

You’re not kidding! I’m on 24 right now and … I’m hitting a lot of dead ends. … its sucking be back in!

/Marcus

By: Taher Shihadeh

Taher Shihadeh — Fri, 05 Oct 2007 16:10:09 +0000

Hey Marcus!
Thanks for the comment. I didn't think anyone was reading :-)
If you want to talk about embarrassing just wait to level 22. *THEN* we can talk about ugly code! ;)
I've been busy this week so I've stopped playing at level 24. But I'll be back soon. I hope the rest of the posts are useful for someone.

By: Marcus

Marcus — Fri, 05 Oct 2007 11:13:37 +0000

The double_steps threw me off, but made me study your snippet cos it is way more KISSable than my hack. my ipython log for that session ... embarrassing.

Your soln inspired me to write another
Thank you!

Using a generator:

def seqSquare(start):
    '''
    <-- remember: 100*100 = (100+99+99+98) + (...  -->
    
    >>> assert reduce( lambda x,y: x+y, seqSquare(100)) == 100 * 100
    >>> assert reduce( lambda x,y: x+y, seqSquare(50)) == 50 * 50
    >>> assert reduce( lambda x,y: x+y, seqSquare(99)) == 99 * 99
    '''
    yield start
    while start > 1:
        start -= 1
        yield start
        yield start

def walkywalky():
    from PIL import Image
    imS = Image.open( 'wire.png')
    imT = Image.new(imS.mode,(100,100))
    
    vector = [ (1,0), (0,1), (-1,0), (0,-1)]
    x,y,p,v = -1,0,0,0
    for steps in seqSquare(100):
        for step in range(steps):
            dx,dy = vector[v%4]
            x,y = x+dx, y+dy
            # print '(%d, %d) == %d' % (x, y, p)
            imT.putpixel((x,y),imS.getpixel((p,0)))
            p += 1
        # print
        v += 1
    imT.show()