PLN - Ideas on how to identify subject and predicate

I started working on a project in my spare time. At the moment I need to know how to identify the subject in a sentence, of course a sentence in Portuguese br is composed of subject + predicate, I'm assuming that all the sentences come in that format and I found 3 means of identifying, through the pronouns or article + noun or through the verb (the subject often comes before the verb). The question is, is there any simpler way of identifying the subject?