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Blitz Support : |
From: Todd Veldhuizen (tveldhui_at_[hidden])
Date: 2003-07-21 07:58:46
Oh! I get it now. Maybe you can use this method, from
blitz/array/slicing.cc:
/*
* After calling slice(int rank, Range r), the array refers only to the
* Range r of the original array.
* e.g. Array<int,1> x(100);
* x.slice(firstRank, Range(25,50));
* x = 0; // Sets elements 25..50 of the original array to 0
*/
template<class P_numtype, int N_rank>
void Array<P_numtype, N_rank>::slice(int rank, Range r);
It's no so convenient that it changes the array view you call the slice()
method on.. If you want a version that behaves better, this should work:
template<class T, int N>
Array<T,N> slice(Array<T,N>& A, int rank, Range r)
{
Array<T,N> x(A);
x.slice(rank,r);
return x;
}
Hope that helps, sorry for the confusion.
Cheers,
Todd
-- Todd Veldhuizen / tveldhui_at_[hidden] / Indiana University Computer Science On Sun, 20 Jul 2003, Alex Fore wrote: > I think what he is trying to say, correct me if I am wrong, is that he would like a way to di this without having to specify all of the range arguments. i.e if we had a rank 3 array, and you wanted to pull out a subarray containing all elements of the array where the firstDimension's index was 5. with slicing one would need to: > > Array<T,3> big_array(10,10,10); > > Array<T,2> subarray; > subarray = big_array(5,Range::all(),Range::all()); > > when it would be nice to have a way to do this by just specifying that you want all elements which are indexed by j in the i'th dimension. > > int i = 0; int j = 5; > > subarray = big_array.sub(i,j); > > But the rank of tensor is a template argument so I dunno if this can be done in a rank - independant way. > -Alex > > On Sun, 20 Jul 2003 13:22:44 -0400 > "Dalal, Navneet" <navneet.dalal_at_[hidden]> wrote: > > > Thanks Todd, > > > > but as I want to write meta programmes, so this way of specifying slicing > > will be different for different dimensions. > > I am looking for dimension independent function or operator. > > > > thanks > > navneet > > > > > -----Original Message----- > > > From: Todd Veldhuizen [mailto:tveldhui_at_[hidden]] > > > Sent: Sunday, July 20, 2003 1:14 PM > > > To: Support list for Blitz++ > > > Subject: Re: [Blitz-support] Sub arrays in blitz meta programming > > > > > > > > > Hi Navneet, > > > > > > Try simply > > > > > > Array<double,1> b = a(5, Range::all()); > > > > > > See the slicing section of the manual for more detail: > > > http://www.oonumerics.org/blitz/manual/blitz02.html#index00087 > > > > > > Cheers, > > > Todd > > > -- > > > Todd Veldhuizen / tveldhui_at_[hidden] / Indiana University > > > Computer Science > > > > > > On Thu, 17 Jul 2003, Dalal, Navneet wrote: > > > > > > > Hi, > > > > > > > > I am writing bilinear interpolation code using blitz > > > arrays. I would like to > > > > write this code for general N-d arrays using meta programming. > > > > > > > > However, I am stuck with one problem: how can I get a sub > > > array along one > > > > particular dimension for a blitz array ? > > > > > > > > What I need is something like this: > > > > > > > > Array<double, 2> a (10, 10); > > > > // init a > > > > > > > > int index = 5; > > > > int firstDimension = 0; > > > > > > > > Array<double,1> b = a.subarray(firstDimension, index); > > > > > > > > // now b points to a(5, range::all) > > > > > > > > > > > > > > > > Is there a function or operator already overloaded for this purpose? > > > > > > > > thanks > > > > navneet > > > > _______________________________________________ > > > > Blitz-support mailing list > > > > Blitz-support_at_[hidden] > > > > http://www.oonumerics.org/mailman/listinfo.cgi/blitz-support > > > > > > > _______________________________________________ > > > Blitz-support mailing list > > > Blitz-support_at_[hidden] > > > http://www.oonumerics.org/mailman/listinfo.cgi/blitz-support > > > > > _______________________________________________ > > Blitz-support mailing list > > Blitz-support_at_[hidden] > > http://www.oonumerics.org/mailman/listinfo.cgi/blitz-support > > > _______________________________________________ > Blitz-support mailing list > Blitz-support_at_[hidden] > http://www.oonumerics.org/mailman/listinfo.cgi/blitz-support >