
Re: How does one get data out of a TemporalData object?
Posted:
Jun 20, 2013 4:02 AM


In article <kprf6q$163$1@smc.vnet.net>, Andy Ross <andyr@wolfram.com> wrote:
Andy,
> My mistake, it only returns the interpolated states, not timevalue > 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 timevalue 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 nonempty 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 > >>>> signalprocessing 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 > >>>> > >>> > > > >

