How to find pattern in an array?

How to find a pattern from a numeric array?

For example, there is a numeric array B and pattern (or mask) A. How to get the pattern location found in B? 

 

>> A = [1 2 3];
>> B = [5,4,3,1,2,3,5,4,1,2,3,4,5];

 

Expected output: 4, 9

 

Answer 1

[MathWorks Support Team]

There is no built-in MATLAB function that performs the exact operation described.

However, you can use a single for-loop and the built-in "all" and "find" functions to create a custom function that will output the desired behavior:

>> function output = pattern(B, A)
>>     SIZE = length(B) - length(A);
>>     match = zeros(1, SIZE);
>>     for i=1:SIZE
>>         match(i) = all(B(i:i-1+length(A)) == A);
>>     end
>>     output = find(match == 1);
>> end

[gwoo]

As @claudio points out below in More Answers, strfind(B, A) does exactly what is requested.

Answer 2

[claudio]

output = strfind(B,A);

[claudio]

No exceptions. if you have a particular request you can submit it to evaluate the specific case

str = sprintf('Special string for \t Karel \t K');
pattern = sprintf('\t');
idxTab = strfind(str,pattern)

idxTab =

    20    28