Use defaultdict to generate the mapping

find_reduced.py

@@ -8,6 +8,7 @@ if len(sys.argv) != 2:
 
 import os
 from os import path
+from collections import defaultdict
 from subprocess import Popen, PIPE
 from functools import cmp_to_key
 from datetime import datetime
@@ -44,19 +45,13 @@ def flatten(l):
         if l: yield l.pop(0)
 
 # read mapping between Gentoo and Debian packages
-deb2gen = dict()
+deb2gen = defaultdict(list)
-gen2deb = dict()
+gen2deb = defaultdict(list)
 with open("./deb2gen_mapping.list") as f:
     for line in f:
         d, g = line.strip().split('\t')
-        if deb2gen.get(d):
         deb2gen[d].append(g)
-        else:
-            deb2gen[d] = [g]
-        if gen2deb.get(g):
         gen2deb[g].append(d)
-        else:
-            gen2deb[g] = [d]
 
 with open("./deb_source_pkgs.list") as f:
     debian_names = [p[4:].strip() for p in f]