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This question already has an answer here: Is there any pythonic way to combine two dicts (adding values for keys that appear in both)? 18 answers I am working with collections.Counter() counters. I would like to combine two of them in a meaningful manner. Suppose I have 2 counters, say, Counter({'menu': 20, 'good': 15, 'happy': 10, 'bar': 5}) and Counter({'menu': 1, 'good': 1, 'bar': 3}) I am trying to end up with: Counter({'menu': 21, 'good': 16, 'happy': 10,'bar': 8}) How can I do this? All you need to do is add them: >>> from collections import Counter >>> a = Counter({'menu': 20, 'good':

This question concerns two implementations of counters which are intended to scale without sharding (with a tradeoff that they might under-count in some situations): http://appengine-cookbook.appspot.com/recipe/high-concurrency-counters-without-sharding/ (the code in the comments) http://blog.notdot.net/2010/04/High-concurrency-counters-without-sharding My questions: With respect to #1: Running memcache.decr() in a deferred, transactional task seems like overkill. If memcache.decr() is done outside the transaction, I think the worst-case is the transaction fails and we miss counting whatever

What is the way to obtain a thread safe counter in C# with best possible performance? This is as simple as it gets: public static long GetNextValue() { long result; lock (LOCK) { result = COUNTER++; } return result; } But are there faster alternatives? This would be simpler: return Interlocked.Increment(ref COUNTER); MSDN Interlocked.Increment Les As recommended by others, the Interlocked.Increment will have better performance than lock() . Just take a look at the IL and Assembly where you will see that Increment turns into a "bus lock" statement and its variable is directly incremented (x86)

The below code is running for first three elements of the tuple of this list SS1=[(1, 2, 3, 4, 5), (1, 2, 3, 4, 6), (1, 2, 3, 5, 6), (1, 2, 4, 5, 6), (1, 3, 4, 5, 6), (2, 3, 4, 5, 6)] from collections import Counter c = Counter(elem[0:3] for elem in SS1) for k, v in c.items(): if (v > 0): print(k,v) and the output is: (1, 2, 3) 3 (1, 2, 4) 1 (1, 3, 4) 1 (2, 3, 4) 1 But my expectation is not just for first three tuple...i want the counter for tuple (0,2,3) or tuple (1,2,4) likewise i can pass any three position of the tuple and get the count of it... How can I do this? If what i understood from

I've these code for searching occurrence in Array-List but my problem is how I can get result out side of this for loop in integer type cause I need in out side , may be there is another way for finding occurrence with out using for loop can you help me ? thank you... List<String> list = new ArrayList<String>(); list.add("aaa"); list.add("bbb"); list.add("aaa"); Set<String> unique = new HashSet<String>(list); for (String key : unique) { int accurNO = Collections.frequency(list, key); System.out.println(key + ": " accurNO); } You should declare a map like Map<String, Integer> countMap = new