Assigning IDs in regular point layer using QGIS

Question

I have a uniform point layer generated by using the Regular Points process. My goal is to connect (draw a line to join) a certain number of points in this points layer in a snake pattern.

My current process in PyQGIS works well with horizontal lines, just following the point "ID"s as I go. It makes it easy to count how many points I've accessed and stop when the limit is reached. However, I am stumped about how I can do this vertically, as the IDs will be fully out of order. Is there a way to force a uniform point field to assign "ID"s vertically instead of from left to right?

Edit: Horizontal "Snake" pattern here; I would like to achieve the same effect vertically. The snaking line would stop at a given # of points reached; once reached, a new line would start. Repeat until all points are reached.

Edit2: Vertical example. Hand-drawn so doesn't line up that well but hope it does the trick to explain the outcome I have in mind:

Answer 1

1. Open FieldCalculator: Make new Field y (float) with $y.
2. Install the QGIS-Plugin "Sort and Number".
3. Open the Plugin. Select your desired layer. For "1st field" select "y". For "New Fieldname" use whatever you want e.g. "id". This tool can overwrite current id Values!