[Tutor] Variations on putpixel - More Pixel manipulation - #14

D. Hartley denise.hartley at gmail.com
Wed Jun 1 19:34:30 CEST 2005

In working out the "two different iterations at once" part, I decided
to do the following:

function that creates a "tolist" (a list of coordinate-pair-tuples,
incremented in the correct way to go around in the direction I want)

and then a for loop to iterate one by one over the wire.png (the "fromlist"):

for i in range(10000):

So the first time through I should get my first "destination" pizel
from tolist, and my first "fill-in" pixel (0,0) from wire.png.  This
part seems pretty ok.

However, I think there must be a problem in my "tolist" creater
function, because the picture it gave me, while completely filled in
with pixels from wire.png, does not make anything recognizeable.  (I
am starting at the top left corner of the new image and filling in in
a spiral - to the right, down, back left, up, and so on):

def findtolist():
    tolist = [(0,0)]
    x = 0
    y = 0
    inc = 1
    numtimes = 100
    while numtimes > 0:
        for i in range(numtimes-1):
            x += inc
            coord = (x,y)
        for i in range(numtimes-1):
            y += inc
            coord = (x,y)
        inc *= -1
        numtimes -= 1
    del tolist[10000:]
    return tolist

However, the list that that function returns is only 9901 items long
(although it DOES end where it should - at (50,50).  What is going on?
Where did those extra 99 pixels go?

Would appreciate any ideas you have!

Thanks again,

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