geometry - Slicing a circle in equal segments, Python -

i have set of close of 10,000 points on sky. plotted using ra (right ascension) , dec (declination) on sky. when plotted, take shape of circle.

enter image description here

what slice circle 8 equal parts , remove each part 1 @ time , calculations using remaining parts.

to came illustration in mind, i.e. slicing them using arcs.

i know equation of arc given by:

s = r * theta

where

r --> radius theta --> angle (in our case 45 degrees)

i somehow like:

slice1 = [] a,b in zip(ra,dec):     if a>some value , a<some value , b>some value , b<some value:         slice1.append(a,b)

if square, becomes easy, , above equation can applied.

so once have slice, can numpy.where() find out rest of circle.

i can slice 4 slices mentioning min(ra),max(ra),min(dec) , max(dec). 1 such example when first quadrant give me this:

ra>0.0 , ra<max(ra) dec>0.0 , dec<max(dec)

enter image description here

i don't know how go doing in case (i.e. 8 quadrants!!), wherein i have x,y coordinates of data points!!

you can compute array of slice numbers directly with numpy operators:

sliceno = numpy.int32((pi + numpy.arctan2(y, x)) * (n / (2*pi)))

meaning:

Brant