How can I check if a cell array contains multiple strings without loops ?

Hi, I have a cell array (1x198) in which every cell contains a string. Each of this string is the name of a test (20-MAG-C-Z1-S0A) and they have an indicator inside de name (S0A,S0B,S0C). For each of them, I want to extrat the position of the string that contain the mentionen indicator, but without a loop, since in same cases i could have more than 100000 tests. The Matlab verison I am using is Matlab R2021b.

I have been trying with different methods to solve it and the most promising was applying cellfun().

FileNames={'20-MAG-C-Z1-S0A','20-MAG-C-Z2-S0A','20-MAG-C-Z1-S0B','20-MAG-C-Z3-S0C','20-MAG-C-Z2-S0B','20-MAG-C-Z1-S0C',....};
p2={'S0A','S0B','S0C'};
index = cellfun(@(c) strcmp(c,FileNames),p2,'UniformOutput',false);

for this case I have obtained 1x3 cell array with 1x198 logical inside him and they are complete empty with no position of the indicator as it should be since 'S01' is no '20-MAG-C-Z1-

index = cellfun(@(c) contains(c,FileNames),p2,'UniformOutput',false);

S0A'. On the other hand if i try with the funtion contains, it return a 1x3 cell array with zero value in all cells.¿Why? It should not have to return a 1x3 cell array with 1x198 logical inside of each of them indicating the position for each indicator ('S0A','S0B','S0C')

Could you give me some guide lines to follow please? The result I want to obtain is position in a way that a could them later manipulate each document i have.

Answer 1

[Paul]

Assuming that numerical indices are desired (as apposed to logical)

% example data
FileNames={'20-MAG-C-Z1-S0A','20-MAG-C-Z2-S0A','20-MAG-C-Z1-S0B','20-MAG-C-Z3-S0C','20-MAG-C-Z2-S0B','20-MAG-C-Z1-S0C'};
FileNames.' % see what they are

ans = 6×1 cell array
    {'20-MAG-C-Z1-S0A'}
    {'20-MAG-C-Z2-S0A'}
    {'20-MAG-C-Z1-S0B'}
    {'20-MAG-C-Z3-S0C'}
    {'20-MAG-C-Z2-S0B'}
    {'20-MAG-C-Z1-S0C'}

p2={'S0A','S0B','S0C'};

% get the desired indices a three element cell array
cellofindices = arrayfun( @(pat)(find(contains(FileNames,pat))),p2(:),'UniformOutput',false)

cellofindices = 3×1 cell array
    {[1 2]}
    {[3 5]}
    {[4 6]}

% might be easier to use if the indices are stored in a structure
s = cell2struct(cellofindices,p2,1)

s = struct with fields:
    S0A: [1 2]
    S0B: [3 5]
    S0C: [4 6]

[Ander Del Olmo Sanz]

It works. Thank you so much for yor help.

Answer 2

[Fangjun Jiang]

>> cell2mat(regexp(FileNames,'S0A|S0B|S0C'))

ans =

13 13 13 13 13 13

[Ander Del Olmo Sanz]

Sorry, but it does not give me the position por each indicator a previusly mention, so I can extract all names for one indicator.