How do I find the number of occurrences of data points between specific values in a matrix?

The following code finds the number of occurrences of data between two points of the same value.

x=[4 1 2 2 2 2 2 2 2 2 2 4 1 2 2 2 2 3 3 4 5 6 1 2 2 2 2 2 2 2 2 2 2 2 3 4 1 2 2 2 2 2];
t=data==8;
out=diff(find(t))-1;

How could one change this code to determine how many data points are between specified data points to choose between?

for example:

If I had this code and I wanted to find the interval between the "1" and the next "4" in sequence how would I go about doing it? I want the code to output the interval of data points between the two specific values for each of the occurrences. From the data given as X the output should be output=[9 6 12]

Any help would be appreciated

[dpb]

How much is known of the data structure a priori? Specifically, is it known the values exist in sequence as shown here (albeit a missing closing '4' after the last initial '1')?

[Joe]

this is just an example data set but the one I normally work with is a 1x600 matrix consisting of values between 1 and 10. It is known that these values occur in a semi-structured way. for example a 1 always precedes a 2 but a 1 can occur without being followed by a 2. I wanted a way to specifically target two numbers in a sequence and find their difference. The problem I am finding is that when I type in the code:

data=[1 2 2 2 2 2 2 2 2 2 3 1 2 2 2 2 7 8 3 8 3 4 5 6 1 2 2 2 ...
    2 2 2 2 2 2 2 2 3 4 1 2 2 2 2 2];

PEI1=data== 1;
PEI3=data==3
PEI1out=diff(find(PEI1-PEI3))-1

it gives me a half right answer PEIout= [9 0 6 1 3 11 1], where the 9, 6, and 11 are correct but the others are not.

Answer 1

[Andrei Bobrov]

data = [1 2 2 2 2 2 2 2 2 2 3 1 2 2 2 2 7 8 3 8 3 4 5 6 1 2 2 2 ...
2 2 2 2 2 2 2 2 3 4 1 2 2 2 2 2];

x = [1 3];
[l1,ii] = ismember(data,x);
i0 = find(l1);
k = strfind(ii(i0),[1 2]);
out = diff([i0(k);i0(k+1)])-1;

[Joe]

This worked! Thanks!