Count how many times a number appears for X number of rows (e.g 99 rows) in an array.

I have a very long array made up of mostly 0s but also has rows with the number 5 in them. The 5s can occur for either 99 rows or 10 rows. In between the rows of either 99 5s or 10 5s, there are 0s. For example [0 0 0 0 5 5 5 5 5 5 5 5 5 5 0 0 0 0 5 5 ... x 99]

I want to write a script that can flag up in the array whenever the long list of 5s (99 rows) begins. The beginning of the list should always preceded by a 0. So far I have written the following code:

k = 1 

for i = 1:length(data) %my array is called 'data'
        
        if (data (i:i+98,3)== 5) & (data(i-1,3) == 0) %look for 5s that last 99 rows, and have a 0 before the first '5'
            ninetyNINEdata {1}(k) = i;
            k = k + 1; %count how many times these 99 rows of 5s occur
        end
end 

The issue is that I get the error 'Index exceeds matrix dimensions' when I run the code. Is there anyway to acheive the same outcome without this error occurring? Thank you!

Answer 1

[Rik]

You have two options:

1. use the runlength function by Jan (you can get it from the File Exchange)
2. replace 1:length(data) by 1:(length(data)-98)

Also, you should replace length(data) by size(data,dim), where dim is the dimension you need.

[Aleya Marzuki]

Thank you!!