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Error with reshape of number of elements

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Fed
Fed on 25 Jan 2019
Commented: Fed on 1 Feb 2019
Hello,
I'm working with multi-class classification by using function fitcecoc.
Featureste is a 1063x22 matrix while Wte is a 1063x1 vector.
Running the code shown below, a message error is given, saying: 'To RESHAPE the number of elements must not change'
Error is given at the following line:
reshape(max(PosteriorRegion,[ ],2),size(x1Grid,1),size(x1Grid,2)))
How can I fix it? Thank you in advance
Mdl = fitcecoc(Featureste,Wte,'Learners',t,'FitPosterior',1,...
'ClassNames',{'1','2','3'},...
'Verbose',2)
%Cross-validate Mdl using 10-fold cross-validation.
CVMdl = crossval(Mdl);
%CVMdl is a ClassificationPartitionedECOC cross-validated ECOC classifier.
%Estimate the classification error.
loss = kfoldLoss(CVMdl);
%Define a grid of values in the observed predictor space.
%Predict the posterior probabilities for each instance in the grid.
xMax = max(Featureste);
xMin = min(Featureste);
x1Pts = linspace(xMin(1),xMax(1));
x2Pts = linspace(xMin(2),xMax(2));
[x1Grid,x2Grid] = meshgrid(x1Pts,x2Pts);
[~,~,~,PosteriorRegion] = predict(Mdl,[x1Grid(:),x2Grid(:)]);
%For each coordinate on the grid
%plot the maximum class posterior probability among all classes.
figure
contourf(x1Grid,x2Grid,...
reshape(max(PosteriorRegion,[],2),size(x1Grid,1),size(x1Grid,2)))
hold on
gh = gscatter(Featureste(:,1),Featureste(:,2),Wte,'krk','*xd',8)
gh(2).LineWidth = 2;
gh(3).LineWidth = 2;
hold off

Accepted Answer

Cris LaPierre
Cris LaPierre on 25 Jan 2019
Here's my guess. You create x1Pts and x2Pts without specifying the number of elements you want. When you do that, you get a vector with length 100. See this comment from the documentation page:
  • y = linspace(x1,x2) returns a row vector of 100 evenly spaced points between x1 and x2.
Therefore, x1Grid and x2Grid and 100x100.
I have no idea what the size of PosteriorRange is, but max(PosteriorRegion,[],2) must NOT be a 10000 x 1 (size(x1Grid,1) = size(x1Grid,2) = 100).
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