Just create an array. Like if you have an array of xCenters and yCenters and zCenters
distances = sqrt(xCenters.^2 + yCenters .^ 2 + zCenters .^ 2);
radialDistribution = zeros(1, length(distances));
for k = 1 : length(xCenters)
thisDistance = round(distances(k)); % Convert distance into an index.
radialDistribution(thisDistance) = radialDistribution(thisDistance) + 1;
end
bar(radialDistribution, 'BarWidth', 1);
grid on;
