A Friday 22 October 2010 20:54:21 braingateway escrigué: > Gaetan de Menten : > > On Fri, Oct 22, 2010 at 10:53, Francesc Alted <fal...@pytables.org> wrote: > >> A Friday 22 October 2010 10:45:13 Francesc Alted escrigué: > >>> A Friday 22 October 2010 10:19:50 Gaetan de Menten escrigué: > >>>> Hello, > >>>> > >>>> I guess you are pretty busy, but I would really appreciate your > >>>> opinion about those two tickets (it's been 3 months without > >>>> reply). I'm willing to make (other) patches, tests or whatever > >>>> you want to get those changes included. Especially 287 is a > >>>> burden for me since I have to distribute my patch along with my > >>>> program and explain to my users how to patch their copy of > >>>> PyTables... So I would like for it to be either included in > >>>> some form, or rejected altogether so that I would work around > >>>> it. > >>> > >>> Yeah, too many things to do lately... Anyway, I plan to release > >>> 2.2.1 next week (let's see). I've had a quick look into #287 and > >>> seems good to me, so I plan to add it to the forthcoming release. > >>> Which is the other you are referring to? > >> > >> Er... you are referring to #286 indeed. I'll try to think about > >> this (of course, a patch would help me think faster :-) > > > > Thanks for the quick reply. I'll produce a patch for #286... in > > time. That one is more a nitpick than anything, so I'll come back > > to it in a few weeks now that I know you are possibly > > interested... > > Hi Gaëtan, > > I am just about to ask for the similar feature. Without this feature, > I have to recreate the Expr object every time I try to change the > start and end position, which is very annoying, although it will not > affect the performance a lot. And the eval() can only be called > once, other wise it is going to give wrong result.
Now that I think, I ended implementing this behaviour because I needed a way to pass a lot of parameters to the computational kernel. For passing such parameters, I implemented the next methods for `Expr`: * setInputsRange(start=None, stop=None, step=None) * setOutput(out, append_mode=False) * setOutputRange(start=None, stop=None, step=None) Do you think that it is better to be able to pass these params to `eval()` instead? Hmm, I'm not that sure... > I try to create an expr object with certain expression, then I am > going to change the input range in a loop, and repeatedly call > expr.eval(). I found out this is impossible, only the first time > calling expr.eval() will work, outputing (10,5) array. Then it > always ouputs the same (5,) array, unless I recreate expr again. Is > this an expected behavior? Recreating the expression (via `Expr` constructor) is very cheap in terms of time. Why do you not like doing this? > By the way, is there any way to set the input range for several > different dimensions? For example, if I get (4e12,100) array: A, and > I probably want to evaluate expression only on A[x:y,2:5]. I think > this will be very useful feature for large arrays. It should be pretty useful indeed. But, for doing this I'm afraid that we'd need to implement something similar to NumPy views, but for PyTables containers (this is how numexpr deals with the problem at least). Unfortunately I don't think this is going to happen anytime soon, so you will need to explicitly *copy* the interesting chunks of the array prior to perform computations. Cheers, -- Francesc Alted ------------------------------------------------------------------------------ Nokia and AT&T present the 2010 Calling All Innovators-North America contest Create new apps & games for the Nokia N8 for consumers in U.S. and Canada $10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store http://p.sf.net/sfu/nokia-dev2dev _______________________________________________ Pytables-users mailing list Pytables-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/pytables-users
