MATLAB Central Newsreader - Insert zeros into a vector

Insert zeros into a vector

Diego Lass — Wed, 24 Jun 2009 23:20:17 -0400

Hi,
I want to insert zeros into a vector in various positions. But not necessarily every other elements. For example
A = [ 1; 3; 4 ;5 ;6;7]
A =
     1
     3
     4
     5
     6
     7
I want to insert at the every 3 rd positon
     1
     3
     0
     4
     5
     0
     6
     7
     0
What is the most efficient way of doing this?
Thanks.
Diego

Re: Insert zeros into a vector

Nathan — Wed, 24 Jun 2009 23:34:02 -0400

On Jun 24, 4:20 pm, "Diego Lass" <dlISC...@gmail.com> wrote:
> Hi,
> I want to insert zeros into a vector in various positions. But not necessarily every other elements. For example
> A = [ 1; 3; 4 ;5 ;6;7]
> A =
> 1
> 3
> 4
> 5
> 6
> 7
> I want to insert at the every 3 rd positon
> 1
> 3
> 0
> 4
> 5
> 0
> 6
> 7
> 0
> What is the most efficient way of doing this?
> Thanks.
> Diego

http://www.mathworks.ch/matlabcentral/newsreader/view_thread/156659

% the data
     v=1:7;
     w=[0,0,0];
     pos=[3,6,9];
% the engine
     tf=false(1,numel(v)+numel(w));
     r=double(tf);
     tf(pos)=true;
     r(tf)=w;
     r(~tf)=v;
% the result
     r

Re: Insert zeros into a vector

Diego Lass — Wed, 24 Jun 2009 23:41:01 -0400

Got it!

>> B = reshape(A, 2, 6/2)

B =

     1 4 6
     3 5 7

>> B = cat(1,B, sparse(1,6/2))

B =

   (1,1) 1
   (2,1) 3
   (1,2) 4
   (2,2) 5
   (1,3) 6
   (2,3) 7

>> B = reshape(B, [], 1 )

B =

   (1,1) 1
   (2,1) 3
   (4,1) 4
   (5,1) 5
   (7,1) 6
   (8,1) 7

>> full(B)

ans =

     1
     3
     0
     4
     5
     0
     6
     7
     0

"Diego Lass" <dlISCool@gmail.com> wrote in message <h1ucbh$f5i$1@fred.mathworks.com>...
> Hi,
> I want to insert zeros into a vector in various positions. But not necessarily every other elements. For example
> A = [ 1; 3; 4 ;5 ;6;7]
> A =
> 1
> 3
> 4
> 5
> 6
> 7
> I want to insert at the every 3 rd positon
> 1
> 3
> 0
> 4
> 5
> 0
> 6
> 7
> 0
> What is the most efficient way of doing this?
> Thanks.
> Diego
>
>