On Feb 7, 12:48 pm, Jussi Salmela <[EMAIL PROTECTED]> wrote: > jeremito kirjoitti: > > > On Feb 7, 8:28 am, "jeremito" <[EMAIL PROTECTED]> wrote: > >> On Feb 6, 5:10 pm, Bruno Desthuilliers > > >> <[EMAIL PROTECTED]> wrote: > >>> jeremito a écrit : > >>> > On Feb 6, 2:36 pm, Bruno Desthuilliers > <[EMAIL PROTECTED]> wrote: > >>> (snip) > >>> >>Here's an alternative implementation, so you get the idea. > >>> >>class Xs(dict): > >>> oops ! I meant: > >>> class Xs(object): > >>> of course... > >>> (snip) > >>>> I guess I just > >>>> need more experience. > >>> Possibly - but not only. You may want to have a look at the > >>> FineManual(tm) for all this kind of "magic", starting with > >>> :http://docs.python.org/ref/specialnames.htmlhttp://docs.python.org/re... > >>> HTH > >> Thanks again! Sometimes the problem is simply not knowing where to > >> find the documentation, or finding the right portion of the > >> documentation. Your help has been invaluable. > > >> Jeremy > > > One more question. I will be asking for the value of cs.xT *many* > > (~millions) times. Therefore I don't want it's value to be calculated > > on the fly. How can I set the value of xT whenever xS, xF, or xG are > > changed, but not allow it to be set directly? From the example given > > previously, it seems like it can't be done this way. > > > Thans, > > Jeremy > > I'm certainly no wizard in timing, but here goes: > > Using the class definition given to you by Bruno, adding the following > to the end (and 'import timeit' at the start): > > #============ > lst = timeit.Timer('for i in xrange(10): xx=xs.xT', \ > 'from __main__ import Xs;xs = Xs()').repeat(100,1000) > lst.sort() > print lst > print 'Average:', sum(lst)/100 > #============ > > I get the output: > [0.017246605364648282, 0.01727426251101738, 0.017275659336591698, > 0.017290745052793044, 0.01733264982001903, 0.017347735536220377, > > and so on ... > > 0.029063749722380933, 0.029163762433493667, 0.029422733894950315, > 0.029790378386079785] > Average: 0.0182474979362 > > Thus: A 1000 assignments take a little over 18 milliseconds. The largest > values in the list are probably caused bu GC occurring. But even 30 ms / > 1000 iterations i.e. 30 microseconds per fetch seems to be fast enough. > > All this depends of course on the computer used. Mine is on the fast > side, you might test it on your PC. > > The correct way of programming is to find a good simple algorithm and > the data structures needed, to program a clean solution with them and > then when you've got a correctly operating application and THEN IF you > need speed try to do something about it. > > "Premature optimization is the worst evil" or something like that is how > the saying goes. > > Hopefully I'm not leading you astray by being a novice in using the > timeit module. > > HTH, > Jussi
Thank you. Once again this mailing list has proven most helpful. I realize it probably isn't worth my time (or stress) to figure out how to avoid calculating xT on the fly-at least not yet. Jeremy -- http://mail.python.org/mailman/listinfo/python-list
