knnsearch error while finding similar images

Hello guys;

I am new to matlab. I am going to make a program that finds similar images. but in the knnsearch i am getting an error. here is my code.

directory1 = fullfile('./buildings');
images1 = dir(fullfile(directory1,'*.jpg'));
names1 = {images1.name}';
directory2 = fullfile('./forest');
images2 = dir(fullfile(directory2,'*.jpg'));
names2 = {images2.name}';
directory3 = fullfile('./sunset');
images3 = dir(fullfile(directory3,'*.jpg'));
names3 = {images3.name}';

buildings=cell(numel(names1),1);
forest=cell(numel(names2),1);
sunset=cell(numel(names3),1);
buildingsHOG=cell(numel(names1)/2,1);
forestHOG=cell(numel(names2)/2,1);
sunsetHOG=cell(numel(names3)/2,1);
buildingsHOGTest=cell(numel(names1)/2,1);
forestHOGTest=cell(numel(names2)/2,1);
sunsetHOGTest=cell(numel(names3)/2,1);

for k=1: numel(names)

      buildings{k} = imread(fullfile(directory1,names1{k}));
      forest{k} = imread(fullfile(directory2,names2{k}));
      sunset{k} = imread(fullfile(directory3,names3{k}));

      if k<=15
          buildingsHOG{k}=HOG(buildings{k});
          forestHOG{k}=HOG(forest{k});
          sunsetHOG{k}=HOG(sunset{k});
      else
          buildingsHOGTest{k-15}=HOG(buildings{k});
          forestHOGTest{k-15}=HOG(forest{k});
          sunsetHOGTest{k-15}=HOG(sunset{k});
      end

end

buildingsResults=cell(numel(names1)/2,7);
forestResults=cell(numel(names2)/2,7);
sunsetResults=cell(numel(names3)/2,7);
for k=1: (numel(names)/2)

      buildingsResults{k}=knnsearch(buildingsHOG,buildingsHOGTest,'k',5);

end

and this is the error:

Error using double
Conversion to double from cell is not possible.

Error in KDTreeSearcher (line 215)
                X = double(X);

Error in createns (line 163)
        O = KDTreeSearcher(X,'distance',distMetric,'bucketSize',bSize, args{:});

Error in knnsearch (line 140)
O=createns(X,args{:},'nsmethod', nsmethod,'bucketSize',bSize);

Error in application2exercise3 (line 45)
    buildingsResults{k}=knnsearch(buildingsHOG,buildingsHOGTest,'k',5);

Best Regards.

Answer 1

[Sean de Wolski]

So either BuildingsHOG or buildingsHOGTest is a cell array (or they both are) and it should be a double.

Perhaps you want to extract one of their elements?

BuildingHog{1} %extract first cell