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