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Topic: How does one get data out of a TemporalData object?
Replies: 7   Last Post: Jun 20, 2013 4:02 AM

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Joseph Gwinn

Posts: 112
Registered: 2/23/05
Re: How does one get data out of a TemporalData object?
Posted: Jun 20, 2013 4:02 AM
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In article <kprf6q$163$1@smc.vnet.net>, Andy Ross <andyr@wolfram.com>
wrote:

Andy,

> My mistake, it only returns the interpolated states, not time-value
> pairs. It is easy enough to get both if you want them though.
>
> Table[{t, data["SliceData", t][[1]]}, {t, 0, 20, .1}]


This worked. I'll suggest (via the prerelease program) that a small
example be added to the online documentation.

Thanks,

Joe



> -Andy
>
> On 6/17/2013 8:08 AM, Andy Ross wrote:

> > Does the following do what you want?
> >
> > Plot[data["SliceData", t], {t, 0, 20}, Filling -> Bottom]
> >
> > The "SliceData" property performs the same interpolation as
> > ListLinePlot in this case (can be controlled via Method option) and
> > returns time-value pairs.
> >
> > -Andy
> >
> > On 6/17/2013 5:29 AM, Joe Gwinn wrote:

> >> In article <kpjvbv$9mc$1@smc.vnet.net>, Andy Ross <andyr@wolfram.com>
> >> wrote:
> >>
> >> Andy,
> >>

> >>> TemporalData has a number of properties for extracting the parts you
> >>> need. To get the paths with time stamps use TemporalData[...]["Paths"].
> >>> To get the states use TemporalData[...]["States"].
> >>>
> >>> I recommend looking at the details section of the documentation for
> >>> TemporalData to see the full list of properties and read through the
> >>> examples on that page to see how each is used.

> >> I had looked over the documentation, and nothing jumped out. I looked
> >> at every mention of TemporalData, and found nothing that seemed
> >> suitable.
> >>
> >> But I didn't try States, so I just did. It yields a list of alternating
> >> 1 and 2 values, which isn't a complete answer to the problem, as the
> >> time values are missing. If one just uses Fourier[], one will get some
> >> kind of Periodogram, which is not what is sought.
> >>
> >> Let me give a code example:
> >>
> >> \[ScriptCapitalP] = ContinuousMarkovProcess[{1, 0}, ({
> >> {-3, 3},
> >> {1, -1}
> >> })];
> >> data=RandomFunction[\[ScriptCapitalP],{0,20}]
> >> Fourier[data]
> >>
> >> This yields a complaint:
> >> Fourier::fftl:
> >> (((((("\"Argument \!\(\*TagBox[\nRowBox[{\\\"TemporalData\\\",
> >> \\\"[\\\", PanelBox[" 1) ", FrameMargins->Small], \\\"]\\\"}],
> >> InterpretTemplate[TemporalData[Automatic, {{{1, 2, 1, 2, 1, 2, 1, 2, 1,
> >> 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1}}, {{{0``15.954589770191005,
> >> 0.01520207123587128013320057817736596917`14.129940038322594,
> >> 0.95824522046395536932862513249273766604`15.644199356725549,
> >> 1.53128564596308252148382664967984035205`15.736304825316484,
> >> 2.28962713530000690099771260582537312886`15.797207858258304,
> >> 3.28670141416927664988333023187555326092`15.839226787640209,
> >> 3.38168097695521799981621844019305806672`15.842081650549387,
> >> 4.0716904019295301685379386805431332727`15.859211783981653,
> >> 5.25370702200219072713176547011226038622`15.878918089214274,
> >> 5.91828379716574832280816964564910319058`15.88678718369098,
> >> 6.12633788645240157414249230434964341735`15.888924305967711,
> >> 6.19666658844600659408879868858704605186`15.889616516866917,
> >> 9.58526332575202981025003709494096121015`15.911492152203763,
> >> 9.8441361181069966832633195553354003832`15.912572420088354,
> >> 14.33613695082054447978910756738149487066`15.925305933162454,
> >> 14.96549983870748084202749476200455050281`15.926498477053611,
> >> 15.17014786638371663403108748271496533041`15.92686559286194,
> >> 15.36161929373388768828517022927544623659`15.927200484830422,
> >> 15.67573549317739061376647722217804251544`15.927732699101226,
> >> 15.8362986262877527919959498312816012794`15.927996832624787,
> >> 16.94396941821241069345266065715083372759`15.929686408696478,
> >> 17.04737697478590359190098510749722701209`15.929833245160726,
> >> 22.73457835309395939446096043959096018021`15.93589515332067}}}, 1, {")
> >> Discrete) ", 1}, {") Continuous) ", 1}, 1, {}}]& ], Editable->False,
> >> SelectWithContents->True, Selectable->True]\) is not a non-empty list
> >> or rectangular array of numeric quantities.\"")
> >>
> >> Now, note that the following appears to work:
> >>
> >> plot1 = ListLinePlot[data, InterpolationOrder -> 0,
> >> PlotRange -> {1, 2.1}, Ticks -> {Automatic, {1, 2, 3}},
> >> Filling -> Bottom]
> >>
> >> But when I do this:
> >>
> >> datainter =
> >> Interpolation[Normal[data] // First, InterpolationOrder -> 0]
> >> plot2 = Plot[datainter[t], {t, 0, 20}, PlotRange -> All,
> >> Filling -> Bottom]
> >>
> >> I get a different answer, and other paths yield yet other answers.
> >>
> >>
> >> What I'm looking for is for instance a function that can be called from
> >> Table[] to yield a list of equispaced samples suitable for Fourier[].
> >> The locations and interval between samples may vary as needed to keep
> >> Fourier happy - list length will be an exact power of two, and there
> >> may be zero padding added.
> >>
> >> Thanks,
> >>
> >> Joe Gwinn
> >>
> >>

> >>> Andy Ross
> >>> Wolfram Research
> >>>
> >>> On 6/15/2013 3:25 AM, Joe Gwinn wrote:

> >>>> I would like to generate some random signals for use in exploring
> >>>> signal-processing algorithms.
> >>>>
> >>>> For use as synthetic signals for the algorithm to chew upon, I'd like
> >>>> to use ContinuousMarkovProcess and TelegraphProcess with
> >>>> RandomFunction. With these, I can do statistics and plot things
> >>>> freely.
> >>>>
> >>>> What I cannot quite get is a time series ready for such indignities as
> >>>> Fourier[].
> >>>>
> >>>> Now I can manually disassemble the data structure, but I don't find a
> >>>> list of equispaced samples, I get a transition list, which is not the
> >>>> same thing.
> >>>>
> >>>> Interpolation[Normal[temporal data object] // First,
> >>>> InterpolationOrder
> >>>> -> 0] almost works, but the fine details are smeared over, even though
> >>>> InterpolationOrder -> 0 works in ListLinePlot et al without apparent
> >>>> smearing.
> >>>>
> >>>> What am I missing? It seems like Probability and Statistics has
> >>>> become
> >>>> a walled city within Mathematica. I'm hoping to find a door in the
> >>>> wall,
> >>>> rather than be forced to build by own little city one brick at a time.
> >>>>
> >>>> Joe Gwinn
> >>>>

> >>>
> >
>
>





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