Sim_SSDD_2013

Sim_SSDD_2013

Sim_SSDD_2013(
  dag,
  terms,
  distance = "shortest_distances_via_NCA",
  verbose = simona_opt$verbose
)

Methods

Sim_SSDD_2013

It is similar as the Sim_Shen_2010 which also sums content along the path passing through LCA term. Instead of summing the information content, the Sim_SSDD_2013 sums up a so-called "T-value":

sim = 1 - atan(sum_{x in the path}(T(x)))/(pi/2)

Each term has a T-value and it measures the semantic content a term averagely inherited from its parents and distributed to its offsprings. The T-value of root is 1. Assume a term t has two parents p1 and p1, The T-value for term t is averaged from its

(w1*T(p1) + w2*T(p2))/2

Since the parent may have other child terms, a factor w1 or w2 is multiplied to T(p1) and T(p2). Taking p1 as an example, it has n_p offsprings (including itself) and t has n_t offsprings (including itself), this means n_t/n_p of information is transmitted from p1 to downstream via t, thus w1 is defined as n_t/n_p.

Paper link: doi:10.1016/j.ygeno.2013.04.010 .