十大免费实用网站刷关键词指数
这篇文章中的降采样方法，适用于直线网格。（我觉得这个在一些对称性较高的网格点中效果才会好）
Lin B, Fu S, Lin Y, Rotondo RL, Huang W, Li HH, Chen RC, Gao H. An adaptive spot placement method on Cartesian grid for pencil beam scanning proton therapy. Phys Med Biol. 2021 Dec 2;66(23):10.1088/1361-6560/ac3b65. doi: 10.1088/1361-6560/ac3b65. PMID: 34798620; PMCID: PMC9311299.
复现完发现不适用于我想要实现的目标（），放出来吧。通过修改代码中的numOfSteps的数量可以进行不同程度的采样，1 <= numOfSteps <= 3。
clear
clc
close allnumOfSteps = 3;
beta = 1;N = 11;
[X, Y] = meshgrid(1:N, 1:N);
spotPosBev = [X(:), Y(:)];% Find the closest point to the geometric center
[~, idx] = min(sum((spotPosBev - mean(spotPosBev,1)).^2, 2));
center = spotPosBev(idx, :);
spotPosBev = spotPosBev - center;
spotIndices = (1:size(spotPosBev,1))';% Calculate number of groups
dist = max(abs(spotPosBev), [], 2);
uniqueDist = unique(dist);
numOfGroups1 = length(uniqueDist);% Initial spot groups and indices
groups = repmat(struct('spotPosBev', [], 'spotIndices', [], 'numOfSpots', []), numOfGroups1, 1);
for i = 1:numOfGroups1mask = (dist == uniqueDist(i));currSpotPosBev = spotPosBev(mask,:);currSpotIndices = spotIndices(mask);% Calculate polar coordinate values[theta, ~] = cart2pol(currSpotPosBev(:, 1), currSpotPosBev(:, 2));[~, order] = sort(theta);groups(i).spotPosBev = currSpotPosBev(order,:);groups(i).spotIndices = currSpotIndices(order);groups(i).numOfSpots = numel(currSpotIndices);
end% Initial
remainingSpots = struct( 'step', num2cell((1:numOfSteps)'),...'posBev', cell(numOfSteps,1), ...'indices', cell(numOfSteps,1), ...'numOfSpots', mat2cell(zeros(numOfSteps,numOfGroups1),ones(1,numOfSteps),numOfGroups1));for j = 1:numOfStepsremainingSpots(j).posBev = cell(numOfGroups1,1);remainingSpots(j).indices = cell(numOfGroups1,1);switch jcase 1for i = 1:numOfGroups1currSpotPosBev = groups(i).spotPosBev;currSpotIndices = groups(i).spotIndices;currNumOfSpots = groups(i).numOfSpots;if currNumOfSpots <= betamask = true(currNumOfSpots,1);elsemask = false(currNumOfSpots,1);if mod(i,2) == 1, mask(2:2:end) = true;else, mask(1:2:end) = true; end endremainingSpots(1).posBev{i} = currSpotPosBev(mask,:);remainingSpots(1).indices{i} = currSpotIndices(mask);remainingSpots(1).numOfSpots(i) = nnz(mask);endcase 2remainingSpots(2).posBev{1} = remainingSpots(1).posBev{1};remainingSpots(2).indices{1} = remainingSpots(1).indices{1};remainingSpots(2).numOfSpots(1) = 1;numOfGroups2 = ceil((numOfGroups1-1)/2);F = false(numOfGroups2,1);F(1:2:end) = true;for i = 1:numOfGroups2if (2*i+1) > numOfGroups1currSpotPosBev = remainingSpots(1).posBev{2*i};currSpotIndices = remainingSpots(1).indices{2*i};currNumOfSpots = remainingSpots(1).numOfSpots(2*i);elsecurrSpotPosBev = [remainingSpots(1).posBev{2*i}; remainingSpots(1).posBev{2*i+1}];currSpotIndices = [remainingSpots(1).indices{2*i}; remainingSpots(1).indices{2*i+1}];currNumOfSpots = remainingSpots(1).numOfSpots(2*i) + remainingSpots(1).numOfSpots(2*i+1);endif currNumOfSpots <= betamask = true(currNumOfSpots,1);else% [theta, ~] = cart2pol(currSpotPosBev(:, 1), currSpotPosBev(:, 2));% [~, order] = sort(theta);% currSpotPosBev = currSpotPosBev(order,:);% currSpotIndices = currSpotIndices(order,:);mask = false(currNumOfSpots,1);if F(i), mask(1:2:end) = true;else, mask(2:2:end) = true; endendcurrSpotPosBev = currSpotPosBev(mask,:);currSpotIndices = currSpotIndices(mask);dist = max(abs(currSpotPosBev), [], 2);for k = 1:numOfGroups1subsetmask = (dist == uniqueDist(k));if any(subsetmask)remainingSpots(2).posBev{k} = currSpotPosBev(subsetmask,:);remainingSpots(2).indices{k} = currSpotIndices(subsetmask);remainingSpots(2).numOfSpots(k) = nnz(subsetmask);endendendcase 3remainingSpots(3) = remainingSpots(2);for i = 2:2:numOfGroups1remainingSpots(3).posBev{i} = [];remainingSpots(3).indices{i} = [];remainingSpots(3).numOfSpots(i) = 0;endotherwiseerror("step must be ≤ 3");end
endfigure
posBev = vertcat(remainingSpots(numOfSteps).posBev{:});
scatter(posBev(:,1), posBev(:,2), 'b', 'filled');
axis equal, box on
for i = 1:numOfGroups1patch('Faces',1:groups(i).numOfSpots,'Vertices',groups(i).spotPosBev, ...'EdgeColor','k','FaceColor','none','LineWidth',2);
end
2025.4.1