MATLAB Central Newsreader - Dataset find and replace problem

Dataset find and replace problem

Bruce Ferguson — Tue, 18 Aug 2009 22:50:17 -0400

I have a dataset array named "sortBA" with three columns and lots of rows (500K+).

I have shown the first twenty rows below:

disp(sortBA(1:20,{'timemilli','cmeB','cmeA'}))

    timemilli cmeB cmeA
    1247146199971 1.3986 1.3989
    1247146199981 0 0
    1247146200001 0 0
    1247146200043 0 0
    1247146200044 0 0
    1247146200049 0 0
    1247146200056 0 0
    1247146200061 0 0
    1247146200081 0 0
    1247146200091 0 0
    1247146200145 1.3986 1.3989
    1247146200188 0 0
    1247146200215 0 0
    1247146200229 0 0
    1247146200250 1.3986 1.3989
    1247146200266 1.3987 1.399
    1247146200290 0 0
    1247146200299 1.3987 1.3989
    1247146200302 0 0
    1247146200303 1.3986 1.399

I need to do a form of "sample and hold" in engineering terms. I want to see if a cell of column "cmeB" or a cell of column "cmeA" contains a zero. If it contains a zero I want to replace the zero with the most recent previous nonzero cells value in that column and continue down the rows until I reach the length of the variable "sortBA".

I have tried everything I can find to do this without luck.

Any help will be greatly appreciated....

Re: Dataset find and replace problem

us — Tue, 18 Aug 2009 23:17:08 -0400

"Bruce Ferguson" <bferguson1@penson.com> wrote in message <h6fb79$dpn$1@fred.mathworks.com>...
> I have a dataset array named "sortBA" with three columns and lots of rows (500K+).
>
> I have shown the first twenty rows below:
>
> disp(sortBA(1:20,{'timemilli','cmeB','cmeA'}))
>
> timemilli cmeB cmeA
> 1247146199971 1.3986 1.3989
> 1247146199981 0 0
> 1247146200001 0 0
> 1247146200043 0 0
> 1247146200044 0 0
> 1247146200049 0 0
> 1247146200056 0 0
> 1247146200061 0 0
> 1247146200081 0 0
> 1247146200091 0 0
> 1247146200145 1.3986 1.3989
> 1247146200188 0 0
> 1247146200215 0 0
> 1247146200229 0 0
> 1247146200250 1.3986 1.3989
> 1247146200266 1.3987 1.399
> 1247146200290 0 0
> 1247146200299 1.3987 1.3989
> 1247146200302 0 0
> 1247146200303 1.3986 1.399
>
> I need to do a form of "sample and hold" in engineering terms. I want to see if a cell of column "cmeB" or a cell of column "cmeA" contains a zero. If it contains a zero I want to replace the zero with the most recent previous nonzero cells value in that column and continue down the rows until I reach the length of the variable "sortBA".
>
> I have tried everything I can find to do this without luck.
>
> Any help will be greatly appreciated....

one of the many solutions is outlined below

% the data
     m=[
          1.2
          0
          2.4
          0
          0
          3.6
          0
          4.8
     ];
% the engine
     ms=cumsum(m~=0);
     md=m(m~=0);
     r=md(ms);
% the result
     disp(r);
%{
          1.2
          1.2
          2.4
          2.4
          2.4
          3.6
          3.6
          4.8
%}

us

Re: Dataset find and replace problem

setijioon junam — Fri, 06 Nov 2009 18:04:02 -0500

"us " <us@neurol.unizh.ch> wrote in message <h6fcpk$rm2$1@fred.mathworks.com>...
> "Bruce Ferguson" <bferguson1@penson.com> wrote in message <h6fb79$dpn$1@fred.mathworks.com>...
> > I have a dataset array named "sortBA" with three columns and lots of rows (500K+).
> >
> > I have shown the first twenty rows below:
> >
> > disp(sortBA(1:20,{'timemilli','cmeB','cmeA'}))
> >
> > timemilli cmeB cmeA
> > 1247146199971 1.3986 1.3989
> > 1247146199981 0 0
> > 1247146200001 0 0
> > 1247146200043 0 0
> > 1247146200044 0 0
> > 1247146200049 0 0
> > 1247146200056 0 0
> > 1247146200061 0 0
> > 1247146200081 0 0
> > 1247146200091 0 0
> > 1247146200145 1.3986 1.3989
> > 1247146200188 0 0
> > 1247146200215 0 0
> > 1247146200229 0 0
> > 1247146200250 1.3986 1.3989
> > 1247146200266 1.3987 1.399
> > 1247146200290 0 0
> > 1247146200299 1.3987 1.3989
> > 1247146200302 0 0
> > 1247146200303 1.3986 1.399
> >
> > I need to do a form of "sample and hold" in engineering terms. I want to see if a cell of column "cmeB" or a cell of column "cmeA" contains a zero. If it contains a zero I want to replace the zero with the most recent previous nonzero cells value in that column and continue down the rows until I reach the length of the variable "sortBA".
> >
> > I have tried everything I can find to do this without luck.
> >
> > Any help will be greatly appreciated....
>
> one of the many solutions is outlined below
>
> % the data
> m=[
> 1.2
> 0
> 2.4
> 0
> 0
> 3.6
> 0
> 4.8
> ];
> % the engine
> ms=cumsum(m~=0);
> md=m(m~=0);
> r=md(ms);
> % the result
> disp(r);
> %{
> 1.2
> 1.2
> 2.4
> 2.4
> 2.4
> 3.6
> 3.6
> 4.8
> %}
>
> us

I think your code( which is really good by the way ) works only on positive data ? is that right ? we should adapt it a bit vectors uncluding negative data ?