There are four char sequences in the name of a matlab variable (say "AaL1.mat" {1} A to I; {2} a to e; {3} low,med,high; {4} 1 to 6 ). How to loop every possible name (from AaL1.mat to IeH6.mat) ?

There are four char sequences in the name of a matlab variable (say "AaL1.mat" {1} A to I; {2} a to e; {3} low,med,high; {4} 1 to 6 ). How to loop every possible name (from AaL1.mat to IeH6.mat) ?

Answer 1

[Stephen23]

 fmt = '%s%s%s%s.mat';
 S1 = 'A':'I';
 S2 = 'a':'e';
 S3 = 'LMH';
 S4 = '1':'6';
 for k1 = 1:numel(S1)
   for k2 = 1:numel(S2)
     for k3 = 1:numel(S3)
       for k4 = 1:numel(S4)
         name = sprint(fmt,S1(k1),S2(k2),S3(k3),S4(k4));
         ...
       end
     end
   end
 end

Make sure that you preallocate any output variables, otherwise this loop will be slow:

https://www.mathworks.com/help/matlab/matlab_prog/preallocating-arrays.html

[Amamcherla Nagaswathi]

Dear Sir, Huge Thanks for your answer:)

Also, How can we make S1 from A1 to A9. It is not working with S1='A1':'A9';

And how can we proceed S3 if instead of L,M,H we need L,Me,Hig

%%

%Preallocation

name = cell(810,1);

 S1 = 'A':'I';
 S2 = 'a':'e';
 S3 = 'LMH';
 S4 = '1':'6';

 i=0;

 for k1 = 1:numel(S1)
   for k2 = 1:numel(S2)
     for k3 = 1:numel(S3)
       for k4 = 1:numel(S4)
           i = i+1;
         name{i,1} = sprintf('%s%s%s%s.mat',S1(k1),S2(k2),S3(k3),S4(k4));
         ...
       end
     end
   end
 end

Thank you very much, Sir.

[Stephen23]

"How can we make S1 from A1 to A9. It is not working with S1='A1':'A9';"

Use a numeric array and change the format string, e.g. (just the relevant lines):

fmt = 'A%d%s%s%s.mat'; % Note 'A%d' at start.
N1 = 1:9;
...
for k1 = 1:numel(N1)
    ...
        sprintf(fmt,N1(k1),...)
    ...
end

"And how can we proceed S3 if instead of L,M,H we need L,Me,Hig"

For multiple characters (rather then just one character at-a-time) you could use strings or a cell array, e.g. (just the relevant lines):

...
C3 = {'L','Me','Hig'};
...
     for k3 = 1:numel(C3)
       ...
         sprintf(fmt,...,C3{k},...) % note {} brackets for cell array indexing!
       ...
     end
...

I would also recommend that you automatically adjust the size of the output array names, so putting it all together you would have something like this:

fmt = 'A%d%s%s%s.mat';
idx = 0;
N1 = 1:9;
S2 = 'a':'e';
C3 = {'L','Me','Hig'};
S4 = '1':'6'
N = numel(N1)*numel(S2)*numel(C3)*numel(S4);
name = cell(N,1); % automatically preallocate the right size
for k1 = 1:numel(V1)
  for k2 = 1:numel(S2)
    for k3 = 1:numel(C3)
      for k4 = 1:numel(S4)
        idx = 1+1;
        name{idx} = sprintf(fmt,N1(k1),S2(k2),C3{k3},S4(k4));
        ...
      end
    end
  end
end

Actually working with strings would make this all much simpler, as you could use the same indexing and format type for all four substrings.

[Amamcherla Nagaswathi]

Great understanding. Thanks a lot.