There is no predicting the trajectory of an Irish woman walking.
If she is coming toward you from the opposite side, it's possible that she will wander in front of you.
If you choose to hold your own space and continue in a straight line, it's possible that you will bump into her. Well, she will bump into you but she will be genuinely surprised to do so. She will be polite about it but surprised.
I suspect that the Irish female tendency to wobble and wander is a cultural adaptation to the biological imperative, the need to reproduce a compulsion supressed by the awful repression of sexuality that the Irish version of the Catholic church imposed upon everybody. Venues for meeting a mating partner were so limited that bumping into people might have been a random way of increasing chances by an increment, since those women who accidentally stumbled into people were more likely to reproduce.
But that's all speculation. What is true is that an Irish woman will step into your path. She will be walking toward your left side, and three meters in front of you will change cant and all of a sudden she'll be walking toward your right side.
She doesn't know you're there. You can change course or you can bump into her. If you bump into her, she will be exquisitely polite because she just didn't see you.-
N.B. I know that all of this is bullshit and that every generalization is ultimately untrue.