Never mind, I figured out that the slice assignment is emptying the previous lists, before the .reset() statements are creating new lists that I then populate and pass on. It makes sense.
On Tue, Dec 31, 2013 at 12:59 AM, Keith Winston <keithw...@gmail.com> wrote: > I resolved a problem I was having with lists, but I don't understand how! > I caught my code inadvertently resetting/zeroing two lists TWICE at the > invocation of the game method, and it was leading to all the (gamechutes & > gameladders) lists returned by that method being zeroed out except the > final time the method is called. That is: the game method below is iterated > iter times (this happens outside the method), and every time gamechutes and > gameladders (which should be lists of all the chutes and ladders landed on > during the game) were returned empty, except for the last time, in which > case they were correct. I can see that doing the multiple zeroing is > pointless, but I can't understand why it would have any effect on the > returned values. Note that self.reset() is called in __init__, so the lists > exist before this method is ever called, if I understand properly. > > def game(self, iter): > """Single game""" > > self.gamechutes[:] = [] #when I take out these two slice > assignments, > self.gameladders[:] = [] # then gamechutes & gameladders work > properly > > self.gamechutes = [] # these were actually in a call to > self.reset() > self.gameladders = [] > > #.... other stuff in reset() > > while self.position < 100: > gamecandl = self.move() > if gamecandl[0] != 0: > self.gamechutes.append(gamecandl[0]) > if gamecandl[1] != 0: > self.gameladders.append(gamecandl[1]) > return [iter, self.movecount, self.numchutes, self.numladders, > self.gamechutes, self.gameladders] > > I'm happy to share the rest of the code if you want it, though I'm pretty > sure the problem lies here. If it's not obvious, I'm setting myself up to > analyse chute & ladder frequency: how often, in a sequence of games, one > hits specific chutes & ladders, and related stats. > > As always, any comments on style or substance are appreciated. > -- Keith
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