Tukukkk

I need help to speed up a function I created to correct x and y elements based on the position of obstacles.

I explain better my function with one example only in the x direction (this means 1D example). Let's suppose I have the values of x and Geometry as

x = [1.8;3.4;4.2;6.3;6.4;8.6;9.1];

Geometry = [0;1;1;0;1;0;1;1;0;0]; % the value 1 means obstacle

So if I do find(Geometry) i'll get the position of the obstacles. Then the function corrects the position based on the x elements that are greater than the position of the obstacles. So for example x(1) is not corrected because its position is not greater than any obstacle. But x(2) will be corrected by two Geometry elements so Corrected_x(2) = 3.4 - 2. The answer of this example is:

Corrected_x = [1.8;1.4;2.2;3.3;3.4;3.6;4.1];

Note that the last element of x is corrected by 5 because the value is greater than the position of the 5 obstacles present in Geometry.

So far I have written a function that does this in 2D and gives me the result I want but it takes too much time. The problem is that Geometry is MxN matrix that I need to go through every row and column since the obstacle are in different positions in each row or column.
The function takes too much time because of the loops going through every row and column, but also because x and y are large arrays.

Any ideas to speed this up?

function [Corrected_x, Corrected_y]= PositionCorrection(x, y, Geometry)    



yRange = floor(min(y)):ceil(max(y));    

xRange = floor(min(x)):ceil(max(x));   

nY = length(yRange); % nRows    

nX = length(xRange); % nCols



%% Save in cell arrays the x and y elements within the ranges   

xPositionCorrected = cell(nY-1,1);   

yPositionCorrected = cell(nX-1,1);   

% Remember the order of the elements  

Rememberpositionx = cell(nY-1,1);  

Rememberpositiony = cell(nX-1,1);   



%% Loop of search and correction of x elements  

for iY = 1:nY-1  

% x elements within yRange    

 xinBinY = x(y(:)>yRange(iY) & y(:)<yRange(iY+1));       

[~,xObstacle] = find(Geometry(iY,:)); % xPosition of the obstacle   

[~,Rememberpositionx{iY,1}] = ismember(xinBinY,x);   

% Correction   

    if isempty(xinBinY)   

        xPositionCorrected{iY,1} = ;     

    elseif isempty(xObstacle)     

        xPositionCorrected{iY,1} = xinBinY;    

    else   

        matrixCorrectedResults = bsxfun(@gt, xinBinY,xObstacle);    

        xCorrection = sum(matrixCorrectedResults,2);    

        xPositionCorrected{iY,1} = xinBinY-xCorrection;   

    end



end



%% Loop of search and correction of y elements  

    for iX = 1:nX-1    

% y elements within xRange    

 yinBinX = y(x(:)>xRange(iX) & x(:)<xRange(iX+1));       

[yObstacle,~] = find(Geometry(:,iX));       

[~,Rememberpositiony{iX,1}] = ismember(yinBinX,y);     

   if isempty(yinBinX)       

        yPositionCorrected{iX,1} = ;    

    elseif isempty(yObstacle)    

        yPositionCorrected{iX,1} = yinBinX;     

    else    

        matrixCorrectedResults = bsxfun(@gt, yinBinX,yObstacle.');     

        yCorrection = sum(matrixCorrectedResults,2);     

        yPositionCorrected{iX,1} = yinBinX-yCorrection;     

    end    

end    

%% Get the original order     

xPositionCorrected(all(cellfun('isempty', xPositionCorrected),2),:) = ;      

Rememberpositionx(all(cellfun('isempty',Rememberpositionx),2),:) = ;     



yPositionCorrected(all(cellfun('isempty', yPositionCorrected),2),:) = ;      

Rememberpositiony(all(cellfun('isempty',Rememberpositiony),2),:) = ;     



% x     

Lx = 1:length(x);     

Corrected_x = cell2mat(xPositionCorrected);     

idx = cell2mat(Rememberpositionx);     

[~,idtemp] = ismember(Lx,idx);    

Corrected_x = Corrected_x(idtemp);     



% y     

Corrected_y = cell2mat(yPositionCorrected);     

idy = cell2mat(Rememberpositiony);     

[~,idtemp] = ismember(Lx,idy);      

Corrected_y = Corrected_y(idtemp);    

end