Vectorize a for loop

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Ramon Ticzon
Ramon Ticzon on 19 Mar 2019
Commented: Ramon Ticzon on 19 Mar 2019
Hi. How can I speed up the process of my for loop code.
function [missingCase] = CaseChecking(bimage)
missingCase = '';
for img = 1:66
mapList = xlsread('map.xlsx',img);
counter=0;
for i = 1:200
if (~bimage(mapList(i,2),mapList(i,1)))
counter=counter+1;
end
end
if counter<50
missingCase = img;
break
end
end

Answers (2)

Andrei Bobrov
Andrei Bobrov on 19 Mar 2019
Please attach your data (bimage,map.xlsx - small example) as mat-file and xlsx-file.
ml = zeros(200,2,66);
for ii = 1:size(ml,3)
ml(:,:,ii) = xlsread('map.xlsx',ii);
end
mlw = permute(ml(:,end:-1:1,:),[1,3,2]);
out = find(~bimage(sub2ind(size(bimage),mlw(:,:,1),mlw(:,:,2))) < 50,'first',1);

Andrei Bobrov
Andrei Bobrov on 19 Mar 2019
Solution for attached data:
[~,sheets] = xlsfinfo('MapList.xlsx');
n = numel(sheets);
ml = cell(n,1);
for ii = 1:n
ml{ii} = xlsread('MapList.xlsx',ii);
end
jj = repelem((1:n)',cellfun('size',ml,1));
A = cat(1,ml{:});
k = accumarray(jj,(1:size(A,1))',[],...
@(x) sum(~bimage(sub2ind(size(bimage),A(x,2),A(x,1)))));
out = find(k < 50,'first',1);
  2 Comments
Ramon Ticzon
Ramon Ticzon on 19 Mar 2019
where is the variable 'missingCase'? also the 'img' variable.
Ramon Ticzon
Ramon Ticzon on 19 Mar 2019
Hi. Im having an error.
Error in CaseChecking (line 14)
@(x) sum(~bimage(sub2ind(size(bimage),A(x,2),A(x,1)))));

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