Skill to get path/ sheet resistance Between Two selected Points

Your title and subsequent question talk about three very different things:
1) resistance of a path
2) sheet resistance
3) point to point resistance in a path

The sheet resistance is a property of the material of the layer that the shapes are drawn on, possibly found in the technology file, or from the foundry.

In essence you need to find the length of a path (or distance between two points along the path) and then you should be able to calculate its resistance.  Here is some sample code for a "path" object - you will need to modify this in order to use it with pathSeg objects:

procedure(CCFgetPathLength(@optional (obj car(geGetSelSet())) )
  let((prevpt x y (length 0.0))
  ;; if no object is selected, and infix is turned on, then
  ;; use the current mouse location to select the object.
  ;; This is for use with a bindkey, i.e. it is set to run
  ;; this procedure when a key is pressed.
  unless(obj
    when(hiGetCIWindow()->infix
      geSelectPoint(nil enterPoint())
      obj = car(geGetSelSet())
    )
  )
  ;; when the selected object is a path object, iterate
  ;; over the list of points and sum the length. This
  ;; assumes orthogonal or 45 degree segments only.
  when(obj~>objType == "path"
    foreach(pt obj~>points
      ;; operate on pairs of points, if no previous point
      ;; then set it to be the same as the first and use
      ;; it in the next iteration.
      if(!prevpt then
        ;; initialise prevpt to be the first point
        prevpt=pt
      else
        ;; regardless of which direction the segment is
        ;; oriented, calculate the distance between the
        ;; two points (Pythagoras).
        x=car(pt) - car(prevpt)
        y=cadr(pt)-cadr(prevpt)
        length = length + sqrt(expt(x 2) + expt(y 2))
        prevpt=pt
      )
    );; foreach
    ;; print the summed length to the CIW, length will
    ;; have a value as it was initialised as 0.0
    printf("Path length: %5.2f\n" length)
    ;; return the length calculated
    length
  );; when selected object is a path
  );; let
);; procedure CCFgetPathLength

Hopefully this can help you to get started?

Regards,

Lawrence.

Also, Virtuoso Electrical Aware Design (EAD) has a point to point resistance capability which is doing a proper resistance extraction; rather than reinventing the wheel (quite a difficult wheel to reinvent too), you might want to consider looking at this tool.

Kind Regards,

Andrew.