set

问题 I'm attempting to compare two arrays of hashes with very similar hash structure (identical and always-present keys) and return the deltas between the two--specifically, I'd like to capture the folllowing: Hashes part of array1 that do not exist in array2 Hashes part of array2 that do not exist in array1 Hashes which appear in both data sets This typically can be achieved by simply doing the following: deltas_old_new = (array1-array2) deltas_new_old = (array2-array1) The problem for me (which

问题 I have a long list of long lists so efficiency is an issue for me. I wondered if there was a neater way of comparing a list of lists other than looping over a list within a loop of the same list (easier to see by example) matchList=[] myList = [ ('a',[1,2,3]), ('b', [2,3,4]), ('c', [3,4,5]), ('d', [4,5,6]) ] tup_num=1 for tup in myList: for tup2 in myList[tup_num:]: id=str(tup[0])+':'+str(tup2[0]) matches=set(tup[1]) & set(tup2[1]) matchList.append((id,matches)) tup_num+=1 print matchList

问题 I'm trying to find the fastest way to solve this problem, say I have a list of lists: myList = [[1,2,3,4,5],[2,3],[4,5,6,7],[1,2,3],[3,7]] I'd like to be able to remove all the lists that are sublists of one of the other lists, for example I'd like the following output: myList = [[1,2,3,4,5],[4,5,6,7],[3,7]] Where the lists [2,3] and [1,2,3] were removed because they are completely contained in one of the other lists, while [3,7] was not removed because no single list contained all those

问题 Note: This is the two-multipliers variation of this problem Given a set A , consisting of floats between 0.0 and 1.0, find a smallest set B such that for each a in A , there is either a value where a == B[x] , or there is a pair of unique values where a == B[x] * B[y] . For example, given $ A = [0.125, 0.25, 0.5, 0.75, 0.9] A possible (but probably not smallest) solution for B is $ B = solve(A) $ print(B) [0.25, 0.5, 0.75, 0.9] This satisfies the initial problem, because A[0] == B[0] * B[1] ,

问题 I'm looking for an algorithm for intersection of two small, unsorted array in very specific condition. Type of array item is just integer or integer-like type. Significant amount of time (about 30~40%?), one or both array might be empty. Arrays are usually very small - usually 1~3 items, I don't expect more than 10. The intersection function will be called very frequently. I don't care about platform dependent solution - I'm working on x86/windows/C++ Both brute-force/sort-and-intersect

问题 When I see the Set.java file in JDK, /** * * <p>This interface is a member of the * <a href="{@docRoot}/../technotes/guides/collections/index.html"> * Java Collections Framework</a>. * * @param <E> the type of elements maintained by this set * * @author Josh Bloch * @author Neal Gafter * @see Collection * @see List * @see SortedSet * @see HashSet * @see TreeSet * @see AbstractSet * @see Collections#singleton(java.lang.Object) * @see Collections#EMPTY_SET * @since 1.2 */ public interface Set<E

问题 I have a table that contains pairs of words in two separate columns. The order of the words is often important, but there are times when I simply want to aggregate based on the two words, regardless of order. Is there a simple way to treat two rows with the same words but with different orders (one row the opposite of the other) as the same "set"? In other words, treat: apple orange orange apple as: (apple,orange) (apple,orange) 回答1: There's no built-in way at this time. As arrays If you

问题 I define intersection of two lists as follows: def intersect(a, b): return list(set(a) & set(b)) For three arguments it would look like: def intersect(a, b, c): return (list(set(a) & set(b) & set(c)) Can I generalize this function for variable number of lists? The call would look for example like: >> intersect([1, 2, 2], [2, 3, 2], [2, 5, 2], [2, 7, 2]) [2] EDIT: Python can only achieve it this way? intersect([ [1, 2, 2], [2, 3, 2], [2, 5, 2], [2, 7, 2] ]) [2] 回答1: Use the *-list-to-argument

问题 I've been using Redis for a while as a backend for Resque and now that I'm looking for a fast way to perform intersect operation on large sets of data, I decided to give Redis a shot. I've been conducting the following test: — x , y and z are Redis sets, they all contain approx. 1 million members (random integers taken from a seed array containing 3M+ members). — I want to intersect x y and z , so I'm using sintersectstore (to avoid overheating caused by data retrieval from the server to the

问题 While trying to answer What is the preferred way to compose a set from multiple lists in Python, I did some performance analysis and came up with a somewhat surprising conclusion. Using python -m timeit -s ' import itertools import random n=1000000 random.seed(0) A = [random.randrange(1<<30) for _ in xrange(n)] B = [random.randrange(1<<30) for _ in xrange(n)] C = [random.randrange(1<<30) for _ in xrange(n)]' for setup, I timed the following snippets: > $TIMEIT 'set(A+B+C)' 10 loops, best of 3