Index exceeds the number of array elements (10)

var=cell(CC.NumObjects,1) 
for j=1:1:n
% clear var
var(j,1)= var(double(image(CC.PixelIdxList{1,j})))

end
%

my code is like this. CC.NumObjects=10 and for example its consists of CC.PixelIdxList{1,1} = 369x1 array. Others consist of arrays like this. "CC.Pixel dxList{1,1}" values in this are pixel indices. I'm trying to measure the variance of the values corresponding to these indices in the image matrix. but it gives this error.

[Dyuman Joshi]

The error is clear - You are trying to access an index for which data does not exist.

It's not clear what you are trying to do with this line of code.

var(j,1)= var(double(image(CC.PixelIdxList{1,j})))

You pre-allocated var as a cell array and then you are trying to use it as a variable? Makes no sense.

Without more information and the data you are working with, it is difficult to suggest how to proceed. It would be better if you could provide those and also, mention the full error you got i.e. all of the red text.

[besaret koçak]

var(j,1)= var(double(image(CC.PixelIdxList{1,j})))

I am trying to collect the variance values in a table with this row.

image(CC.PixelIdxList{1,j}) This function could be like this image(52) or image(100) or image(150) . 52 and 100 values are array indices. For example:

CC.PixelIdxList{1,7}

result

ans =

       26661
       26662
       26917
       26918
       26919
       27174
       27175
       27176
       27431
       27432
       27433
       27688
       27689
       27690
       27945
       27946
       27947
       28202
       28203
       28204
       28459
       28460
       28461
       28716
       28717
       28718
       28973
       28974
       28975
       29230
       29231
       29232
       29487
       29488
       29489
       29744
       29745
       29746
       30001
       30002
       30003
       30258
       30259
       30260
       30515
       30516
       30517
       30772
       30773
       30774

I should point out here that the image consists of a 255x237 matrix. So there are 255x237=60435 indeces. Here I take the indexes of certain regions and extract their values in the image matrix, like this:

GPR(CC.PixelIdxList{1,7})


ans =

  50×1 uint8 column vector

   117
   117
   116
   118
   117
   116
   117
   117
   116
   117
   118
   116
   118
   117
   117
   117
   117
   117
   118
   117
   117
   117
   117
   116
   117
   117
   116
   117
   116
   117
   117
   117
   117
   117
   117
   117
   117
   117
   116
   117
   116
   116
   117
   116
   116
   117
   116
   116
   116
   116

Here, the equivalent of 26661 index is given as 117. others in the same way. I want to find the variance of these values. When I remove this code from the for loop and run it for the first time, it does not give an error, but the second time I run it, I get this error.

 Index exceeds the number of array elements (10).

Error in imageContour (line 26)
var(j,1)= var(double(GPR(CC.PixelIdxList{1,j})))

[Dyuman Joshi]

I guess you are trying to do this -

var = cell(CC.NumObjects,1);
for j = 1:n
var{j,1} = double(image(CC.PixelIdxList{1,j})));
end

[besaret koçak]

There is no variance here because there is no code. When I write the code, it gives the same error again. So like this

var = cell(CC.NumObjects,1);
for j = 1:n
var{j,1} = var(double(image(CC.PixelIdxList{1,j})));
end

[Dyuman Joshi]

Attach the data you are working with. Use the paperclip button to do so.

Once again, why are you trying to use an empty cell array as a variable as and then over-writing it?

var{j,1} = var(double(image(CC.PixelIdxList{1,j})));

Edit - I seemed to have forgotten that var is a built-in MATLAB function :')

[besaret koçak]

Dyuman Joshi Thank you for your help :)

Answer 1

[Voss]

Avoid naming your variable var, since that is the name of a function you are trying to use. Also, a cell array doesn't appear to be required; you can use a numeric vector to store the results.

var_result = zeros(n,1);
for j = 1:n
    var_result(j,1) = var(double(GPR(CC.PixelIdxList{1,j})));
end

[besaret koçak]

Thank you, the error has been resolved. I changed the variable name from "var" to "var_result" and it did not give an error.

[Voss]

You're welcome!