How to make a new matrix from find function results of different size

I have a matrix of IC 2008x1 that has values from 1 to 16 (some in between number might be missing) and I want to create a matrix that each column has the rows of the original matrix that correspond to each value 1 to 16 eg original matrix 4; 1; 3; 2; 5; 6; 4; new matrix [2] [4] [3] [1;7] [5] [6]

I try to do this like this for j=1:B

 k=find(IC==j);
  F(:,j)=k;

end where B is 16 but it says that Subscripted assignment dimension mismatch. Do you know an alternative that works regaldless of this mismatch?

Answer 1

[Ameer Hamza]

In a normal array, all rows and columns must have equal length. You need to use a cell array

for j=1:B
  k=find(IC==j);
  F{j}=k;
end

[Georgios Tertikas]

thanx it works

[Georgios Tertikas]

do you know how i could save this new file in text file in tabular form? (its a cell array file)

[Ameer Hamza]

Try this

f = fopen('test.txt', 'w');
for i=1:numel(F)
  fprintf(f, [repmat('%f ', 1, numel(F{i})), newline], F{i});
end
fclose(f);

[Georgios Tertikas]

I run it and it says undefined variable 'x' or class 'x'

[Ameer Hamza]

There was a typo, updated the code.

[Georgios Tertikas]

now its says undefined variable or function newline

[Ameer Hamza]

You must be using R2016a or earlier. It that case, change the line like this

printf(f, [repmat('%f ', 1, numel(F{i})), 10], F{i});