construct_forest.py

def construct_forest(X, trees_count, subsample_count):
  """The function constructs a forest from given inputs/data points X.
  """
  forest = []
  for i in range(0, trees_count):
    # max_height is in fact the average height of the tree that would be
    # constructed from given points. This acts as max_height for the
    # construction because we are only interested in data points that have
    # shorter-than-average path lengths, as those points are more likely
    # to be anomalies.
    max_height = math.ceil(math.log2(subsample_count))

    # create a sample with cardinality of `subsample_count` from X
    X_sample = get_sample(X, subsample_count)

    # construct the decision tree from the sample
    tree = construct_tree(X_sample, 0, max_height)

    # add the tree to the forest
    forest.append(tree)

  return forest