R/IntersectPoint.R

In stmueller/pathmapping: Compute Deviation and Correspondence Between Spatial Paths

IntersectPoint <-
function(A, B, C)
  {

    if(all(A==B))
      {
        return (0)
      }
      ##This gives a proportion of AB that the
      ##orthogonal line passing through C meets. If outside (0,1)
      ##it does not pass through AB

      ##the surrounding c() transforms this from a matrix to a scaler value.
    c(((B-A) %*% (C-A)) / ((B-A) %*% (B-A)))
  }