Re: sparsearray and its nonempty cells
- To: mathgroup at smc.vnet.net
- Subject: [mg72607] Re: sparsearray and its nonempty cells
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Fri, 12 Jan 2007 05:13:36 -0500 (EST)
- Organization: The Open University, Milton Keynes, UK
- References: <eo4oa3$mhi$1@smc.vnet.net>
Arkadiusz.Majka at gmail.com wrote:
> Hi,
>
> I bulit the following sparse array
>
> Mysparse=SparseArray[i_ /; 2 â?¤ i â?¤ 11 :> 0.8, 20]
>
> in order to find out all nonempty cells in this array I call (I want to
> avoid Normal)
>
>
> Mysparse/. SparseArray[_, _, _, x_] :> x[[2, 2]]
>
> and I get
>
> {{8}, {11}, {3}, {7}, {2}, {6}, {10}, {9}, {5}, {4}}
>
> This is of course correct, but why it is not sorted????
>
> How can I build Mysparse to get sorted list of nonempty cells?
>
> Arek
Hi Arek,
What about the following:
In[1]:=
Mysparse = SparseArray[i_ /; 2 <= i <= 11 :> 0.8, 20];
Sort[Mysparse /. SparseArray[_, _, _, x_] :> x[[2,2]]]
Out[2]=
{{2}, {3}, {4}, {5}, {6}, {7}, {8}, {9}, {10}, {11}}
HTH,
Jean-Marc