I'm going to yell back at a woman on the train
Why would you yell at her?
She was rude to me a few minutes ago, and is still yelling.
I think it's reasonable for you to yell at her in this case, because her behavior was inappropriate. I wouldn't take it to far, though. Just let her know that what she did was not right.
Then I am going to beat her up too after that.
Oh wow, that won't be good. Yelling is okay in some instances but beating people up is not. If you're feeling that angry I think it would be best if you removed yourself from the situation and tried to calm down.