X Y scatter data Color Contour of Frequency Distribution spatially in 125km circle

I have X-Y scatter data. I plotted Frequency Distribution spatially with 5km box resolution, I need values outside 125km radius to show white instead of 0. I understand NaN is the option. How do I implement NaN selectively through code

my code is

binmin = -125; binmax = 125; binwidth = 5;
xbin = 1 + floor((X(:) - binmin) / binwidth);
ybin = 1 + floor((Y(:) - binmin) / binwidth);
nbins = ceil((binmax - binmin) / binwidth);
counts = accumarray([xbin, ybin], 1, [nbins, nbins]);
figure(1)
surf(counts,'EdgeColor','none','LineStyle','none');
view(-270,-90);

any help shall be appreciated

Answer 1

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#How_do_I_create_a_circle.3F

[Utsav]

Thats okay, circlePixels will produce an array of 0 and 1. \ But I have some embedded zero within the circle of 1 too as well as outside How to selectively filter out the outside zeros.