On Wed, 09 Apr 2014 13:24:32 -0700, John Ladasky wrote: > I would like to build a multi-dimensional array that allows numpy-style > indexing and, ideally, uses Python's familiar square-bracket and slice > notations. > > For example, if I declare a two-dimensional array object, x, then x[4,7] > retrieves the element located at the 4th row and the 7th column. If I > ask for x[3:6,1:3], I get a 3 x 2 array object consisting of the > intersection of the 3rd-5th rows, and the 1st-2nd columns, of x. > > In this case I'm not allowed to use numpy, I have to restrict myself to > the standard library. I thought that I might achieve the desired > behavior by defining an object with specific __getitem__ and/or > __getslice__ methods.
Use __getitem__, __getslice__ is deprecated in Python 2 and gone in Python 3. https://docs.python.org/2/reference/datamodel.html#object.__getslice__ > However, the documentation of these methods that > I am reading suggests that the arguments are pre-parsed into certain > formats which may not allow me to do things numpy's way. Is this true? Why don't you try it in the interactive interpreter and see? py> class Test(object): ... def __getitem__(self, thing): ... print thing ... py> obj = Test() py> obj[1] 1 py> obj[1:2] slice(1, 2, None) py> obj[1:2:3] slice(1, 2, 3) py> obj[1,5:2:3] (1, slice(5, 2, 3)) py> obj[1:2:3,4:5:6] (slice(1, 2, 3), slice(4, 5, 6)) py> obj[1,2,3] (1, 2, 3) py> obj[1,2,"spam"] (1, 2, 'spam') py> obj[1,2,"spam":"eggs",3] (1, 2, slice('spam', 'eggs', None), 3) -- Steven -- https://mail.python.org/mailman/listinfo/python-list
