Walking circle_perimeter

[Johannes Schönberger]

This should do the trick…

import numpy as np
import pylab
from skimage.draw import circle_perimeter

img = np.zeros((41, 41))
rr, cc = circle_perimeter(20, 20, 18)

SKIP_SIZE = 3

img[rr, cc] = 5

for i in range(4):
    rri = rr[i::4]
    cci = cc[i::4]
    rri_sorted = np.argsort(rri)
    rri = rri[rri_sorted]
    cci = cci[rri_sorted]
    cci_sorted = np.argsort(cci)
    rri = rri[cci_sorted]
    cci = cci[cci_sorted]
    img[rri[::SKIP_SIZE], cci[::SKIP_SIZE]] = 1

pylab.imshow(img, interpolation='nearest')
pylab.show()


Johannes Schönberger

Am 28.05.2013 um 18:43 schrieb Dan Farmer <dfarmernv at gmail.com>:

> Hi Guys,
> 
> I'm trying to subsample the points returned by circle_perimeter and I'm having trouble. Since the points are calculated in octants (and reflected?) it makes walking it somewhat confusing (see below) Does anyone know off hand how I could walk this thing clockwise for example (or produce a sensible subsample of e.g., every other point or every 4th point, etc).
> 
> To be a little more concrete:
> 
> from skimage.draw import circle_perimeter
> 
> rr, cc = circle_perimeter(12, 12, 10)
> im = zeros((40,40))
> im[rr[::4],cc[::4]] = 1
> imshow(im, cmap=cm.gray)
> # returns one quadrant of the circle
> 
> Still Googling, but I'd appreciate any help =)
> 
> Thanks,
> Dan
> 
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