Question

I have a struct array named Lst. Every struct has the following form:

Point (x,y)
Type (1-6)

I want get the separate array of points for each type. How can I get it?

Lst(Lst.Type==1);

won’t work since Type is not a field of Lst but of Lst(i).

In addition, is there a way to save the indexes of each item or an alternative way to then combine them again to the original order?

Answer 1

L1 = Lst([Lst.Type]==1); will give you the subset L1 of Lst where Type == 1.

Likewise, you can use idx1 = find([Lst.Type]==1) to memorize your indexes.

EDIT: the above uses the [] operator to aggregate the field elements Type of Lst into an array. To your comment/question, you could use the exact same operator also to obtain an array of specific field elements X of a subset of the structured array, as in

X1 = [Lst([Lst.Type]==1).X];