add pseudocount to weighted score to prevent missing single reads

HiLiveViral.py

@@ -349,7 +349,7 @@ def print_treedata(readcountdict, uniquebasesdict, backgrounddict, bsl_dict, res
                 weighted_score = uniquebasesdict[key] / len(
                     backgrounddict[key]) * math.log(speciesnum) # ratio of number of unique fore- and background bases
             else:
-                weighted_score = uniquebasesdict[key] * math.log(speciesnum)
+                weighted_score = uniquebasesdict[key] * (math.log(speciesnum)+1) # add pseudocount to circumvent 0-scores for one read
         try:
             basesnum = uniquebasesdict[key]
         except KeyError:  # references without unique foreground bases are missing in uniquebasesdict