The Variable appears to change size on every loop iteration

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[num_class,num_instance]=size(Outputs);
temp_Outputs=[];
temp_test_target=[];
for i=1:num_instance
temp=test_target(:,i);
if((sum(temp)~=num_class)&&(sum(temp)~=-num_class))
*temp_Outputs=[temp_Outputs,Outputs(:,i)];
temp_test_target=[temp_test_target,temp];*
end
end
Error: The Variable "temp_Outputs" appears to change size on every loop iteration
Question : I have No clue how to Preallocate it ?? Please help !!

Accepted Answer

per isakson
per isakson on 19 Mar 2014
Edited: per isakson on 19 Mar 2014
This is not an error, it's a warning. It is inefficient to change size of a variable in a loop.
However, the if-statement makes it difficult to know the final size in advance, which is "needed" to preallocate.
IMO: don't care about the warning if the execution time is ok. It is possible to suppress it.
See:
  3 Comments
Mahmoud Emad
Mahmoud Emad on 8 Apr 2020
What if I had an execution time problem with a code very similar to this, my vector also is created by conactenation in a for loop, is there an efficient alternative ?

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