Find the existence of a character from a struct

There is a structure with multiple fields and one of them is LOC, for example

 n=5;
 for i=1:n
    S(i).LOC='LL';
 end

From this struct, can someone please help me to find:

1) Whether 'LL' exist in the field LOC or not?

2) And how many times it is repeated?

(Note: the above written code is not what Im working on, its just to give some idea.)

Answer 1

[Stephen23]

Using a comma-separated list and strcmp makes this very simple:

>> S(1).LOC = 'LL';
>> S(2).LOC = 'X';
>> S(3).LOC = 'LL';
>> S(4).LOC = 'LL';
>> S(5).LOC = 'X';
>> strcmp({S.LOC},'LL') % the existence
ans =
   1  0  1  1  0
>> nnz(strcmp({S.LOC},'LL')) % the number
ans =  3

or use strfind if 'LL' can be inside a longer string.

[Asim Ismail]

Thanks @ Stephen Cobeldick for this wonderful piece of code. What about to check the existence of 'LL'?

[Stephen23]

"What about to check the existence of 'LL'?"

It is not clear what output you expect from "the existence", but if you want a single logical output to indicate if 'LL' occurs in any of the structure elements, then simply wrap the strcmp in any:

>> any(strcmp({S.LOC},'LL')) % the existence
ans =
   1

If you mean something else, then please explain clearly what you expect the output top be when measuring the "existence".

[Asim Ismail]

Thats what I was asking for, Thanks a lot again

[OCDER]

Cool solution!

Answer 2

[OCDER]

I think this works. Not the most efficient, but gets the job done.

n=5;
for i=1:n
   S(i).LOC='LL';
end

FoundLL = 0; %Counts how many LL's there in in S structure array
for j = 1:length(S) %Go over every structure in S
   Fields = fieldnames(S(j)); %Find the fields in this structure
   for k = 1:length(Fields) %Go over every field in S
       if strcmp(Fields{k}, 'LOC') %If you have the LOC field name
           CurValue = S(j).(Fields{k}); %Get the value of this field
           if ~isempty(CurValue) && ischar(CurValue) && strcmp(CurValue, 'LL')
               FoundLL = FoundLL + 1;
           end
       end
   end
end

 fprintf('Found this many "LL" in "LOC" field of structure S: %d\n', FoundLL)

[Stephen23]

Errr... you might like to learn about the simpler ways to use MATLAB, that do not rely on nested loops and ifs. This is MATLAB, not C++.

[Asim Ismail]

Thank you @Donald Lee, you actually combined both my questions into this single code. I wanted to do them separately. Anyway how to check just the existence of 'LL'?

[OCDER]

Yup, matlab if and for are slow.