Finding the max value in a vector

Hi guys, I am having some trouble finding the highest value and its Index in a vector. Bellow is my code, I am having trouble in the line:

 [V,M]=max(SUB,{},'omitnan')

The last value from "SUB"is:

Columns 1 through 7
[]    [NaN]    [13.6623]    [-42.7241]    [191.0598]    [-6.5336]    [-33.3556]
Columns 8 through 10
[-62.5169]    [113.4669]    [-24.7364]

That is why it is necessary to use 'omitnan'.

Thanks in Advance !

%importar dados do excel
imp = xlsread('Academia.xlsx');

%%Loop Kmeans K clusters

k=10
% eva = evalclusters(x,clust,criterion)
for i=1:k
     [idx,C]=kmeans(imp,i);
     M{i}=idx;
%     y=xlswrite('Academia.xlsx',idx,'D1:D80')
    eva = evalclusters(imp, idx, 'CalinskiHarabasz')
    CH{i}=eva.CriterionValues
end

% %  Descobrir as diferenças entre os valores de CH
while i>1
    SUB{i}=CH{i}-CH{i-1}
    i=i-1;
end

%Achar o pulo maximo entre os clusters para o valor de CH:
[V,M]=max(SUB,{},'omitnan')

Answer 1

[Walter Roberson]

You do not have a numeric vector, you have a cell array. You cannot use max() on a cell array.

You could consider using cell2mat() to construct a numeric array, and calculate the maximum of that, but then you are left with the question of whether the empty SUBS{1} should be counted as taking up a space or not.

Is there a reason you are storing SUBS as a cell array and not as a numeric array initialized to infinity ?

Answer 2

[Geoff Hayes]

Gabriel - according to max input arguments, a cell array is not a valid input to this function. Are you observing the error

 Undefined function 'max' for input arguments of type 'cell'.

If this is the case, then try converting the cell array to a matrix using cell2mat as

 [V,M]=max(cell2mat(SUB));

where

 V =
  191.0598

 M =
  4

[Gabriel]

Thank you a lot, Geoff , but for some reason I am getting a diferent output: V =

218.6589

M =

     3

Do u know why we get different answers?

[Walter Roberson]

Your sample input that you show does not even have a 281.6589, so either you are applying max() to a different cell that you posted or else you have your own max.m that is making up answers.

[Gabriel]

I think i found the reason in this part of the code:

SUB2=cell2mat(SUB)
 [V,M]=max(SUB2)

SUB = 

    Columns 1 through 7

      []    [NaN]    [22.1828]    [190.8772]    [-33.2118]    [-18.3891]    [-63.9705]

    Columns 8 through 10

      [70.6695]    [-26.9859]    [-78.7988]

SUB2 =

         NaN   22.1828  190.8772  -33.2118  -18.3891  -63.9705   70.6695  -26.9859  -78.7988

V =

    190.8772

As you can see, when the conversion is made it ignores the first i ([]) so that the new index is 3.

Do you know how not to ignore it ?

Thanks !

M =

       3

[Walter Roberson]

I wrote before "You could consider using cell2mat() to construct a numeric array, and calculate the maximum of that, but then you are left with the question of whether the empty SUBS{1} should be counted as taking up a space or not." but you did not answer that.

[Gabriel]

Sorry. Yes, it should be counted.