Making an Array out of another Array if conditions are met

Hello!

So I have a double array that is 15369x9. I am attempting to make a raster plot from this but inorder to do so i need to break the raw data array down into two different arrays, specifically one that has all of the trial starts in it( indicated by a number 1 in the 5th column) and licks(indicated by a 0 in the 5th column) I know I need to use a for loop to index through the array and I want to use an if loop to generate the new array, but I have no real idea how to do that. Any help would be greatly appreciated. Thanks!

Answer 1

[James Tursa]

You don't need a for-loop for this. The best way is to use logical indexing. See this link:

https://www.mathworks.com/help/matlab/math/array-indexing.html?searchHighlight=logical%20indexing&s_tid=srchtitle_logical%2520indexing_2

Basically, you create a logical vector with the conditions you want, and then use that to index into the variable. E.g.,

M = your matrix

M(:,5) is the 5th column of the matrix

x = M(:,5)==1 is a logical vector indicating where there is a 1 in the 5th column

M(x,:) is a subset of M where there is a 1 in column 5.

Etc.

[Rachael Bell]

My data is currently in array form, can i still do that or do i need to do some kind of conversion? Also I forgot to mention it in my main post but I do need to keep at the first column information( timestamps) and the sixth column information( Trial Number) It seems like if I used logical operators I will loose my trial number

[James Tursa]

The method shown retains the entire rows where the column data matches your desired value. I did make an edit to my original post so be sure to grab the latest code shown.