A Dimarts 13 Febrer 2007 19:49, escriguéreu: > Hello Francesc. > > >Mmm, after considering this a bit more seriously, I think that I'll go > > towards > > >implementing the alternative: > > > >row.fetch_all_fields() > > > >because: > > > >- It would be simpler and more efficient to implement (i.e. > > Row.__getitem__ will not be cluttered with more logic). > > > >- Accepting a [:] would make users think that complete extended slicing > > suport > > >(like [colstart:colstop:colstep]) would be implemented and it will be not > > (at > > >least initially). > > I think that slicing is very easy to implement if we have something like > fetch_all_fields which will return a list: > > def __getslice__(self, a, b): > return self.fetch_all_fields().__getslice__(a,b) > > , so both ways can be implemented at once.
That would be nice, but unfortunately, things are not so easy. First, __getslice__() is deprecated, so I'll assume that you mean __getitem__. Second, NumPy doesn't support slices (even not integers!) in scalar record types (the kind of values I'm thinking to be returned by .fetch_all_fields()), as can be seen in: In [54]: a=numpy.array((1,2,"asa"), "i2,i2,a3") In [55]: a['f0'] # name fields are the only indexes allowed Out[55]: 1 In [56]: a[1] --------------------------------------------------------------------------- <type 'exceptions.IndexError'> Traceback (most recent call last) /home/faltet/python.nobackup/Pyrex-0.9.5.1a/<ipython console> in <module>() <type 'exceptions.IndexError'>: 0-d arrays can't be indexed In [57]: a[:] --------------------------------------------------------------------------- <type 'exceptions.ValueError'> Traceback (most recent call last) /home/faltet/python.nobackup/Pyrex-0.9.5.1a/<ipython console> in <module>() <type 'exceptions.ValueError'>: cannot slice a 0-d array And thirdly, even though NumPy would eventually support a generalized slicing for scalar records, Row.__getitem__ is very carefully tuned (i.e. it has low level logic inside) for dealing only with field names. So, just doing things like: return self.fetch_all_fields().__getitem__(...) is a simplistic aproximation that would render unusable many of the existing optimizations in Row.__getitem__(). Cheers, -- >0,0< Francesc Altet http://www.carabos.com/ V V Cárabos Coop. V. Enjoy Data "-" ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier. Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Pytables-users mailing list Pytables-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/pytables-users
