Simplify and speed up duplicate rate checking (pynucastro#692)

This speeds up the sensitivity analysis example code by ~10-15%.

pynucastro/rates/known_duplicates.py

@@ -1,32 +1,25 @@
+import collections
+
 # there are some exceptions to the no-duplicate rates restriction. We
 # list them here by class name and then fname
 ALLOWED_DUPLICATES = [
- (("ReacLibRate: p_p__d__weak__bet_pos_"),
- ("ReacLibRate: p_p__d__weak__electron_capture"))
+ {"ReacLibRate: p_p__d__weak__bet_pos_",
+ "ReacLibRate: p_p__d__weak__electron_capture"}
 ]
 
 
 def find_duplicate_rates(rate_list):
- """given a list of rates, return a list of groups of duplicate
- rates"""
+ """given a list of rates, return a list of groups of duplicate rates"""
 
- duplicates = []
+ # Group the rates into lists of potential duplicates, keyed by their
+ # reactants and products.
+ grouped_rates = collections.defaultdict(list)
  for rate in rate_list:
- same_links = [q for q in rate_list
- if q != rate and
- sorted(q.reactants) == sorted(rate.reactants) and
- sorted(q.products) == sorted(rate.products)]
-
- if same_links:
- new_entry = [rate] + same_links
- already_found = False
- # we may have already found this pair
- for dupe in duplicates:
- if new_entry[0] in dupe:
- already_found = True
- break
- if not already_found:
- duplicates.append(new_entry)
+ grouped_rates[tuple(sorted(rate.reactants)),
+ tuple(sorted(rate.products))].append(rate)
+
+ # any entry in grouped_rates containing more than one rate is a duplicate
+ duplicates = [entry for entry in grouped_rates.values() if len(entry) > 1]
 
  return duplicates
 
@@ -35,17 +28,7 @@ def is_allowed_dupe(rate_list):
  """rate_list is a list of rates that provide the same connection
  in a network. Return True if this is an allowed duplicate"""
 
- for allowed_dupe in ALLOWED_DUPLICATES:
- found = 0
- if len(rate_list) == len(allowed_dupe):
- found = 1
- for r in rate_list:
- rate_key = f"{r.__class__.__name__}: {r.fname}"
- if rate_key in allowed_dupe:
- found *= 1
- else:
- found *= 0
- if found:
- return True
-
- return False
+ # make rate_list into a set of strings in the same format as
+ # ALLOWED_DUPLICATES, then check if it matches any of the allowed sets
+ key_set = {f"{r.__class__.__name__}: {r.fname}" for r in rate_list}
+ return key_set in ALLOWED_DUPLICATES