Merge pull request #6 from ianzur/citation-common-phrase-div-by-zero

Citation common phrase div by zero

src/academic_tracker/helper_functions.py

@@ -669,7 +669,7 @@ def _compute_common_phrase_percent(prev_citation, new_citation, characters_to_re
         min_len (int): the minimum length of a subphrase.
     
     Returns:
-        ((int, int)|None): if either citation is None, then return None, else the percentage of common to uncommon phrase length for each citation.
+        ((int, int)|None): if either citation is None or empty after character removal and stripping, then return None, else the percentage of common to uncommon phrase length for each citation.
     """
     if prev_citation and new_citation:
         citation_strip_regex = "|".join([f"\{char}" for char in characters_to_remove])
@@ -685,8 +685,12 @@ def _compute_common_phrase_percent(prev_citation, new_citation, characters_to_re
             prev_citation_common_phrases_removed = prev_citation_common_phrases_removed.replace(phrase.strip(), "")
             new_citation_common_phrases_removed = new_citation_common_phrases_removed.replace(phrase.strip(), "")
         common_base_string = "".join(common_subphrases)
-        prev_common_percentage = len(common_base_string) / len(common_base_string + prev_citation_common_phrases_removed.strip()) * 100
-        new_common_percentage = len(common_base_string) / len(common_base_string + new_citation_common_phrases_removed.strip()) * 100
+        prev_common_denom = len(common_base_string + prev_citation_common_phrases_removed.strip())
+        new_common_denom = len(common_base_string + new_citation_common_phrases_removed.strip())
+        if prev_common_denom == 0 or new_common_denom == 0: 
+            return None
+        prev_common_percentage = len(common_base_string) / prev_common_denom * 100
+        new_common_percentage = len(common_base_string) / new_common_denom * 100
 
         return prev_common_percentage, new_common_percentage
     else: