+import sys
+sys.path.append("..")
+sys.path.append("../similarities")
+from similarities.similarities_helper import read_tfidf_matrix, reindex_tfidf, reindex_tfidf_time_interval
+
+# this is the mean of the ratio of the overlap to the focal size.
+# mean shared membership per focal community member
+# the input is the author tf-idf matrix