Helmut Jarausch wrote: > On Tue, 03 Dec 2013 13:38:58 +0100, Peter Otten wrote: > >> Helmut Jarausch wrote: >> >>> Hi, >>> >>> I'd like to extracted elements from a heapq in a for loop. >>> I feel my solution below is much too complicated. >>> How to do it more elegantly? >>> I know I could use a while loop but I don't like it. >>> >>> Many thanks for some lessons in Python. >>> >>> Here is my clumsy solution >>> >>> from heapq import heappush, heappop >>> # heappop raises IndexError if heap is empty >>> >>> H=[] >>> for N in 'H','C','W','I' : >>> heappush(H,N) >> >> H = ["H", "C", "W", "I"] >> heapq.heapify(H) >> >> But see below. >> >>> # how to avoid / simplify the following function >>> >>> def in_sequence(H) : >>> try : >>> while True : >>> N= heappop(H) >>> yield N >>> except IndexError : >>> raise StopIteration >>> >>> # and here the application: >>> >>> for N in in_sequence(H) : >>> print(N) >> >> If you are iterating over the complete heap I see no advantage over a >> sorted list. So >> >> for N in sorted(H): >> print(N) >> >> If H is huge use H.sort() instead of sorted() to save memory. >> If you need only a few items use heapq.nsmallest(). > > > Many thanks! > In my real application the data which is pushed onto the heap will be > extracted from a small file which is executed several thousands times. So, > I thought, I could keep the CPU a bit busy while the OS is doing file I/O. > Of course, I could have appended all these strings to a list which is > sorted at the end.
In that case have a look at bisect.insort() which adds an item to a list while keeping it sorted. -- https://mail.python.org/mailman/listinfo/python-list
