Alguém pode explicar a distorção dinâmica do tempo para determinar a similaridade de séries temporais?

14

Estou tentando entender a medida dinâmica de distorção do tempo para comparar séries temporais juntas. Eu tenho três conjuntos de dados de séries temporais como este:

T1 <- structure(c(0.000213652387565, 0.000535045478866, 0, 0, 0.000219346347883, 
0.000359669104424, 0.000269469145783, 0.00016051364366, 0.000181950509461, 
0.000385579332948, 0.00078170803205, 0.000747244535774, 0, 0.000622858922454, 
0.000689084895259, 0.000487983408564, 0.000224744353298, 0.000416449765747, 
0.000308388157895, 0.000198906016907, 0.000179549331179, 9.06289650172e-05, 
0.000253506844685, 0.000582896161212, 0.000386473429952, 0.000179839942451, 
0, 0.000275608635737, 0.000622665006227, 0.00036075036075, 0.00029057097196, 
0.000353232073472, 0.000394710874285, 0.000207555002076, 0.000402738622634, 
0, 0.000309693403531, 0.000506521463847, 0.000226988991034, 0.000414164423276, 
9.6590360282e-05, 0.000476689865573, 0.000377572210685, 0.000378967314069, 
9.25240562546e-05, 0.000172309813044, 0.000447627573859, 0, 0.000589333071408, 
0.000191699415317, 0.000362943471554, 0.000287549122975, 0.000311688311688, 
0.000724112961622, 0.000434656621269, 0.00122292103424, 0.00177549812586, 
0.00308008213552, 0.00164338537387, 0.00176056338028, 0.00180072028812, 
0.00258939580764, 0.00217548948513, 0.00493015612161, 0.00336344416683, 
0.00422716412424, 0.00313360554553, 0.00540144648906, 0.00425728829246, 
0.0046828437633, 0.00397219463754, 0.00501656412683, 0.00492700729927, 
0.00224424911165, 0.000634696755994, 0.00120550276557, 0.00125313283208, 
0.00164551010813, 0.00143575017947, 0.00237006940918, 0.00236686390533, 
0.00420336269015, 0.00329840900272, 0.00242005185825, 0.00326554846371, 
0.006217237596, 0.0037103784586, 0.0038714672861, 0.00455830066551, 
0.00361747518783, 0.00304147465438, 0.00476801760499, 0.00569875504121, 
0.00583855136233, 0.0050566695728, 0.0042220072126, 0.00408237321963, 
0.00255222610833, 0.00123507616303, 0.00178136133508, 0.00147434637311, 
0.00126742712294, 0.00186590371937, 0.00177226406735, 0.00249154653853, 
0.00549127279859, 0.00349072202829, 0.00348027842227, 0.00229555236729, 
0.00336862367661, 0.00383477593952, 0.00273999412858, 0.00349618180145, 
0.00376108175875, 0.00383351588171, 0.00368928059028, 0.00480028982882, 
0.00388823582602, 0.00745054380406, 0.0103754506287, 0.00822677278011, 
0.00778350981989, 0.0041831792162, 0.00537228238059, 0.00723645609231, 
0.0144428396845, 0.00893333333333, 0.0106231171714, 0.0158367059652, 
0.01811729548, 0.0207095263821, 0.0211700064641, 0.017604180993, 
0.0165804327375, 0.0188679245283, 0.0191859923629, 0.0269251008595, 
0.0351239669421, 0.0283510318573, 0.0346557651212, 0.0270022042616, 
0.0260845175767, 0.0349758630112, 0.0207069247809, 0.0106362024818, 
0.00981093510475, 0.00916507201128, 0.00887198986058, 0.0073929115025, 
0.00659077291791, 0.00716191546131, 0.00942304513143, 0.0106886280007, 
0.0123527175979, 0.0171022290546, 0.0142909490656, 0.0157642220699, 
0.0265140538974, 0.0194395354708, 0.0241685144124, 0.0229897123662, 
0.017921889568, 0.0155115839714, 0.0145263157895, 0.017609281127, 
0.0157671315949, 0.0190258751903, 0.0138453217956, 0.00958058335108, 
0.0122924304507, 0.00929741151611, 0.00885235535884, 0.00509319462505, 
0.0061314863177, 0.0063104189044, 0.00729117134253, 0.010843373494, 
0.0217755443886, 0.0181687353841, 0.0155402963498, 0.017310022503, 
0.0214746959003, 0.026357827476, 0.0194751217195, 0.0196820590462, 
0.0184317400812, 0.0130208333333, 0.0128666035951, 0.0120045731707, 
0.0122374253228, 0.00874940561103, 0.0114368092263, 0.00922893718369, 
0.00479041916168, 0.00644107774653, 0.00775830595108, 0.00829578041786, 
0.00681348095875, 0.00573782551125, 0.00772002058672, 0.0112488083889, 
0.00908907291456, 0.0157722638969, 0.00994270306707, 0.0134179772039, 
0.0126050420168, 0.0113648781554, 0.0153894803415, 0.0126959699913, 
0.0116655865198, 0.0112065745237, 0.0122006737686, 0.010251878038, 
0.010891174691, 0.0148273273273, 0.0138516532618, 0.0136552722011, 
0.00986993819758, 0.0097852677358, 0.00889011089726, 0.00816723383568, 
0.00917641660931, 0.00884466556108, 0.0182179529646, 0.0183156760639, 
0.0217806648835, 0.0171099125907, 0.0186579938377, 0.019360390076, 
0.0144603654529, 0.0177730696798, 0.0153226598566, 0.0134016909516, 
0.0126480805202, 0.0115501519757, 0.0127156322248, 0.0124326204138, 
0.0240245215806, 0.0130234933606, 0.0144222706691, 0.00854005693371, 
0.0053560967445, 0.00504132231405, 0.00288778877888, 0.00593526847816, 
0.00455653279644, 0.00433014040152, 0.00535770564135, 0.0131095962244, 
0.0126319758673, 0.0154982879798, 0.0125940464508, 0.0169948745616, 
0.0257535512184, 0.0256175663312, 0.0265191262043, 0.0228974403622, 
0.0193122555411, 0.0165794768612, 0.015658837248, 0.0168208578638, 
0.0129912843282, 0.0119498443154, 0.0112663755459, 0.00838112042347, 
0.00925767186696, 0.0113408269771, 0.0210861519924, 0.0156036134684, 
0.0121687119728, 0.011006497812, 0.0107891491985, 0.0134615384615, 
0.0147229755909, 0.015756893641, 0.0176257128046, 0.016776075857, 
0.0169553999263, 0.0179193118984, 0.0190055672874, 0.0183088625509, 
0.0155489923558, 0.0152507401094, 0.0160748342567, 0.0161532350605, 
0.0139190952588, 0.0161469457497, 0.0118186629035, 0.0109259765092, 
0.00950587391265, 0.00928986154533, 0.00815520645549, 0.00702576112412, 
0.00709539362541, 0.00827287768869, 0.0104688211197, 0.0130375888927, 
0.0160891089109, 0.0188415910677, 0.0203265044814, 0.0183175033921, 
0.0139940353292, 0.0124648170487, 0.0131685758095, 0.00957428620277, 
0.0119647893342, 0.00835800104475, 0.0101892285298, 0.00904207699194, 
0.00772134522992, 0.00740740740741, 0.00776823249863, 0.00642254601227, 
0.00484237572883, 0.00361539964823, 0.00414811817078, 0.00358072916667, 
0.00433306007729, 0.00485008818342, 0.00905280804694, 0.00931847250137, 
0.00779271381259, 0.00779912497622, 0.00908230842006, 0.0058152538582, 
0.0102777777778, 0.00807537012113, 0.00648535564854, 0.0145492582731, 
0.00694127317563, 0.00759878419453, 0.00789242911429, 0.00635050701629, 
0.00785233530492, 0.00607964332759, 0.00531968282646, 0.00361944157187, 
0.00305157155935, 0.00276327909119, 0.00318820364651, 0.00184464029514, 
0.00412550211703, 0.00516567972786, 0.00463655399342, 0.00702897308418, 
0.0100714154917, 0.00791168353266, 0.00959190791768, 0.00736, 
0.00738007380074, 0.012573964497, 0.0117919562013, 0.00842919476398, 
0.00778887565289, 0.00623967700496, 0.0062232955601, 0.00447815755803, 
0.00511135450894, 0.00502557659517, 0.00330328263712), .Tsp = c(1, 
15.9583333333333, 24), class = "ts")

T2 <- structure(c(0, 0, 0, 0, 0.000109673173942, 0, 0, 0, 0, 0, 0, 
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9.66183574879e-05, 0, 
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9.43930526713e-05, 
0, 0, 0, 8.95255147717e-05, 0, 0, 0, 0, 0.000191699415317, 0.000207792207792, 
0, 0, 0, 0.00019727756954, 0.000205338809035, 0.000205423171734, 
0.000704225352113, 0.000450180072029, 0.000493218249075, 0.000120860526952, 
0.000410846343468, 0.000384393619066, 0.000643264105863, 0.000189915487608, 
0.000915499404925, 0.000185099490976, 0.000936568752661, 0.000451385754266, 
0.000757217226692, 0.000273722627737, 0.000187020759304, 0.000211565585331, 
0.000141823854772, 9.63948332369e-05, 0.000117536436295, 0.000287150035894, 
0, 0, 0.000400320256205, 0.000388048117967, 0.000345721694036, 
0.000296868042155, 0.000609533097647, 0.000424043252412, 0.000290360046458, 
0.000546996079861, 0.000556534644282, 0.00036866359447, 0.000275077938749, 
0.000964404699281, 0.00152310035539, 0.00113339145597, 0.00061570938517, 
0.000362877619523, 0.000472634464505, 0.000102923013586, 0.000187511719482, 
0.000294869274622, 0.00011522064754, 0.000248787162582, 0, 0.00035593521979, 
0.000392233771328, 0.000551166636046, 0.000165727543918, 0.000143472022956, 
0.00012030798845, 0.000438260107374, 0.000195713866327, 0.000184009568498, 
0.000537297394108, 0.000365096750639, 0.000102480016397, 0.000452857531021, 
0.000180848177955, 0.000770745910765, 0.00219818869252, 0.000357685773048, 
0.000362023712553, 0.000660501981506, 0.000419709560984, 0.000488949735967, 
0.00177758026886, 4e-04, 0.000475661962898, 0.000879816998064, 
0.0014942099365, 0.00378173960022, 0.00274725274725, 0.00192545729611, 
0.0016462841016, 0.00176238855484, 0.00260780478718, 0.00447289949132, 
0.0034435261708, 0.00290522941294, 0.002694416055, 0.0041329904482, 
0.00729244577412, 0.0296930503689, 0.00982375036117, 0.00453023439039, 
0.00327031170158, 0.00221573169503, 0.00211237853823, 0.00108719286801, 
0.00131815458358, 0.000983008004494, 0.00132253265002, 0.00227790432802, 
0.00247054351957, 0.00307455803228, 0.0029314767314, 0.00222755311857, 
0.00492610837438, 0.00454430699318, 0.00753880266075, 0.00671845475541, 
0.00590490003108, 0.00288356368698, 0.00294736842105, 0.00248601615911, 
0.00197089144936, 0.00326157860404, 0.00302866414278, 0.00202256759634, 
0.00258788009489, 0.00169043845747, 0.00137000737696, 0.000433463372345, 
0.000908368343363, 0.000805585392052, 0.00142653352354, 0.00189328743546, 
0.00558347292016, 0.00161899622234, 0.00162631008312, 0.00276960360048, 
0.00585673524553, 0.00519169329073, 0.0045125282033, 0.00562344544176, 
0.00322815786733, 0.00330528846154, 0.00255439924314, 0.00285823170732, 
0.00240894199268, 0.00218735140276, 0.00201826045171, 0.00168701002282, 
0.000460617227084, 0.00127007166833, 0.00109529025192, 0.000819336337567, 
0.00158170093685, 0.000588494924231, 0.00120089209127, 0.00305052430887, 
0.00161583518481, 0.00211579149837, 0.0010111223458, 0.00346270379455, 
0.00228091236495, 0.00207627581685, 0.00295140718878, 0.0022121765894, 
0.00240718451995, 0.00224131490474, 0.0031867431485, 0.00176756517897, 
0.00233382314807, 0.00178303303303, 0.00169794459339, 0.00162778079219, 
0.000737939304492, 0.00135906496331, 0.000733205022454, 0.000875060768109, 
0.00114705207616, 0.000967385295744, 0.00182179529646, 0.00359130903214, 
0.00420328620558, 0.00446345545843, 0.00376583361862, 0.00659687365553, 
0.00433810963586, 0.00353107344633, 0.00333955407131, 0.00341788091383, 
0.0024939877082, 0.00538428137212, 0.00906989151698, 0.00773778473309, 
0.0210421671775, 0.00859720803541, 0.00511487506289, 0.00406669377796, 
0.00117164616286, 0.00206611570248, 0.00107260726073, 0.00148381711954, 
0.000741761152909, 0.00104973100643, 0.00110305704381, 0.00209753539591, 
0.00452488687783, 0.00486574157506, 0.00850507033039, 0.0101159967629, 
0.0163991223005, 0.0150452373691, 0.0156443766097, 0.0112310639039, 
0.00635593220339, 0.00627766599598, 0.00583041812427, 0.00622371740959, 
0.00624897220852, 0.00420769166036, 0.00305676855895, 0.00291133656815, 
0.00120006857535, 0.00501806503412, 0.00490575781048, 0.00593119810202, 
0.00226874291018, 0.00304999336958, 0.00339087546239, 0.00541958041958, 
0.00445563734986, 0.00431438754455, 0.0038016243304, 0.0037928519329, 
0.00491460867428, 0.00460782305959, 0.00508734881935, 0.00300725278613, 
0.00390896455872, 0.00367811967345, 0.00953591862683, 0.00529614264278, 
0.00243584167029, 0.00427167876976, 0.00291056623743, 0.00227624510607, 
0.00439422473321, 0.00232246538633, 0.00317623830372, 0.00263466042155, 
0.00180200473026, 0.00190912562047, 0.0034896070399, 0.00338638672536, 
0.00548090523338, 0.00697836706211, 0.00720230473752, 0.00746268656716, 
0.00367056664373, 0.0032167269803, 0.00523135203391, 0.00299196443837, 
0.00299119733356, 0.00287306285913, 0.00154657933042, 0.00214861235452, 
0.00163006177076, 0.00157407407407, 0.00137086455858, 0.00124616564417, 
0.000790591955727, 0.00107484854407, 0.00121408336706, 0.00108506944444, 
0.00105398758637, 0.000881834215168, 0.00184409052808, 0.00237529691211, 
0.0013637249172, 0.00190222560396, 0.00264900662252, 0.00156564526951, 
0.00263888888889, 0.00183531139117, 0.00303347280335, 0.0120768352986, 
0.00365330167139, 0.00351443768997, 0.00263080970476, 0.0029703984431, 
0.00265143789517, 0.0014185834431, 0.00150557061126, 0.00144777662875, 
0.00111890957176, 0.000716405690308, 0.000797050911627, 0.000512400081984, 
0.000868526761481, 0.00113392969636, 0.00134609632067, 0.00240013715069, 
0.00128181651712, 0.00110395584177, 0.00156958493198, 0.00208, 
0.00184501845018, 0.00110946745562, 0.000736997262582, 0.00208250694169, 
0.00229084578026, 0.00137639933933, 0.00111462010032, 0.000822518735149, 
0.00200803212851, 0.000987166831194, 0.00041291032964), .Tsp = c(1, 
15.9583333333333, 24), class = "ts")

T3 <- structure(c(0.00192287148809, 0.00149812734082, 0.00192410475681, 
0.00151122625216, 0.00120640491336, 0.00167845582065, 0.00121261115602, 
0.000802568218299, 0.00109170305677, 0.00250626566416, 0.00273597811218, 
0.00242854474127, 0.00160915430002, 0.00124571784491, 0.00192943770673, 
0.00329388800781, 0.00191032700303, 0.00156168662155, 0.00174753289474, 
0.0014917951268, 0.00143639464943, 0.000543773790103, 0.000929525097178, 
0.00141560496294, 0.000966183574879, 0.000719359769805, 0.00190740419629, 
0.00137804317869, 0.00197177251972, 0.001443001443, 0.00203399680372, 
0.00158954433063, 0.00256562068285, 0.00228310502283, 0.00302053966975, 
0.00227352221056, 0.00263239393001, 0.00202608585539, 0.00272386789241, 
0.00269206875129, 0.0027045300879, 0.00276480122033, 0.00405890126487, 
0.00341070582662, 0.00351591413768, 0.00336004135436, 0.00358102059087, 
0.00257289879931, 0.00235733228563, 0.00239624269146, 0.00136103801833, 
0.000862647368926, 0.00145454545455, 0.00168959691045, 0.00246305418719, 
0.0020964360587, 0.00335371868219, 0.00390143737166, 0.00349219391947, 
0.00334507042254, 0.00255102040816, 0.00332922318126, 0.00386753686246, 
0.00246507806081, 0.00432442821449, 0.00312442565705, 0.00408318298357, 
0.00375354756019, 0.00416473854697, 0.00263942103023, 0.0028888688273, 
0.00321817321344, 0.00310218978102, 0.002150738732, 0.00296191819464, 
0.00134732662034, 0.00221708116445, 0.00152797367184, 0.00157932519742, 
0.00220077873709, 0.00207100591716, 0.00260208166533, 0.00310438494373, 
0.00311149524633, 0.00385928454802, 0.00292575886871, 0.00222622707516, 
0.00329074719319, 0.00282614641262, 0.00287542899545, 0.00221198156682, 
0.00311754997249, 0.00315623356128, 0.00287696733796, 0.00296425457716, 
0.00263875450787, 0.00208654631226, 0.00179601096512, 0.00164676821737, 
0.00206262891431, 0.00235895419697, 0.00241963359834, 0.0028610523697, 
0.00516910352976, 0.00160170848905, 0.00254951951363, 0.00275583318023, 
0.00298309579052, 0.00286944045911, 0.00288739172281, 0.00394434096636, 
0.00254428026226, 0.00285214831171, 0.0034924330617, 0.00246440306681, 
0.00266448042632, 0.00389457476678, 0.00253187449136, 0.00171276869059, 
0.00184647850171, 0.00134132164893, 0.00153860077835, 0.000990752972259, 
0.00117518677075, 0.00312927831019, 0.00188867903566, 0.0024, 
0.00269541778976, 0.00263945099419, 0.00242809114681, 0.00378173960022, 
0.00274725274725, 0.00165039196809, 0.00211665098777, 0.00290275761974, 
0.00149017416411, 0.00105244693913, 0.00309917355372, 0.00240432779002, 
0.00297314875035, 0.0015613519471, 0.00196335078534, 0.00227707441479, 
0.00279302706347, 0.00295450068938, 0.00316811446091, 0.00211501661799, 
0.00168990283059, 0.00195694716243, 0.00131815458358, 0.00112343771942, 
0.00214911555629, 0.00157701068863, 0.00171037628278, 0.00230591852421, 
0.00183217295713, 0.00102810143934, 0.00130396986381, 0.00151476899773, 
0.00188470066519, 0.00220449296662, 0.00238267895991, 0.00238639753406, 
0.00147368421053, 0.00113942407292, 0.0018192844148, 0.00152207001522, 
0.00151433207139, 0.00117096018735, 0.000862626698296, 0.00095087163233, 
0.00137000737696, 0.00119202427395, 0.00170319064381, 0.000805585392052, 
0.0012680297987, 0.00189328743546, 0.00186115764005, 0.000719553876597, 
0.000903505601735, 0.000865501125151, 0.00210241778045, 0.00146432374867, 
0.00130625816411, 0.0011895749973, 0.00135374362178, 0.00120192307692, 
0.00160832544939, 0.0015243902439, 0.00240894199268, 0.00218735140276, 
0.00230658337338, 0.00188548179022, 0.0016582220175, 0.00263086274154, 
0.00155166119022, 0.00204834084392, 0.00194670884536, 0.00308959835221, 
0.00154400411734, 0.00152526215443, 0.00343364976772, 0.00269282554337, 
0.00235928547354, 0.00230846919636, 0.00300120048019, 0.00327833023713, 
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0.000897397547113, 0.00222869878279, 0.00201428309833, 0.00202391904324, 
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0.00167193015047, 0.00201060135259, 0.00219058050383, 0.00233330341919, 
0.000963457435827), .Tsp = c(1, 15.9583333333333, 24), class = "ts")

Eu sei que T1 e T2 estão correlacionados e os consideramos verdade terrestre, portanto, qualquer métrica de distância deve me dizer que (T1, T2) estão mais próximos que (T2, T3) e (T1, T3). No entanto, ao usar dtwno R, recebo o seguinte:

> dtw(T1, T2, k = TRUE)$distance; dtw(T1, T3, k = TRUE)$distance; dtw(T3, T2, k = TRUE)$distance
[1] 1.107791
[1] 1.568011
[1] 0.4102962

Alguém pode explicar como usar o Dynamic Time Warping para consultas dos vizinhos mais próximos?

lenda
fonte
1
Você poderia explicar o que você quer dizer com "consulta ao vizinho mais próximo" neste contexto e como ela está relacionada ao dtw?
whuber
@whuber: Minha impressão da DTW foi que é uma métrica de distância para séries temporais. E há este artigo indicando que: Faster Retrieval with a Two-Pass Dynamic-Time-Warping Lower Boundpor Daniel Lemire et. tudo com o código fornecido em code.google.com/p/lbimproved No entanto, estou tentando entender essa métrica antes de usá-la.
Legend

Respostas:

22

A distorção dinâmica do tempo faz uma suposição específica no seu conjunto de dados: um vetor é uma série não linear do tempo . Mas também assume que os valores reais estão na mesma escala.

x=1..10000uma(x)=1pecado(0,01x)b(x)=1pecado(0,01234x)c(x)=1000pecado(0,01x)

umabumacumacumab

O DTW não é sua arma mágica para resolver todas as suas necessidades de correspondência de séries temporais. Faz suposições específicas sobre o tipo de semelhança em que você está interessado . Se isso não corresponder aos seus dados, não funcionará bem. A julgar pelas séries de dados que você compartilhou, você não precisa de alinhamento temporal (o que a DTW faz), mas, na verdade, alguma normalização apropriada e talvez transformações de fourier. As distâncias de travessia de área de lazer também podem funcionar bem para você, veja, por exemplo:

  • Pesquisa de similaridade em séries temporais com base em consultas de limite
    Johannes Aßfalg, Hans-Peter Kriegel, Peer Kröger, Peter Kunath, Alexey Pryakhin e Matthias Renz, EDBT 2006
Tem QUIT - Anony-Mousse
fonte
+1 Obrigado por suas sugestões. Você também poderia me indicar algum trabalho sobre as transformações de Fourier? E, finalmente, fiquei pensando - existem implementações práticas por aí que eu possa experimentar? Quero dizer, alguns bancos de dados que realmente implementam isso em ação.
Legend
1
Ao pesquisar mais sobre isso, deparei-me com o trabalho de representação simbólica SAX de Keogh et. todos da Univ. de Riverside. Você teria algum comentário sobre isso?
Legend
Um amigo experimentou o SAX para séries temporais de movimento (ou seja, classificação de movimento). Não funcionou para ele. Por isso não sugeri. Keogh produz papéis como loucos, mas eles não são muito convincentes no IMHO. Ele deve ter proposto pelo menos 10 leilões de distância para séries temporais, que obviamente superam um ao outro.
Saiu - Anony-Mousse
2
@Anony Eu me ofendo com “Keogh produz papéis como loucos, mas eles não são muito convincentes no IMHO. Ele deve ter proposto pelo menos 10 funções a distância para séries temporais, é claro que todas se superam. ”NÃO propus“ pelo menos 10 funções a distância para séries temporais ”. Eu defendo fortemente 2 funções à distância para séries temporais 1) Distância euclidiana (DE): dois mil anos 2) DTW: 50 anos Essas duas medidas são usadas em 90% dos meus artigos, e eu também não propus ou inventei. Propus pequenas alterações no ED e no DTW. Você diz que "eles não são muito convincentes no IMHO". ...
2
Testo com experimentos reproduzíveis em todos os conjuntos de dados públicos do mundo e dou todo o meu código. Talvez algumas pessoas aqui estejam tendo dificuldade em usar uma das minhas idéias, mas mais de 2.000 pessoas tenham usado com sucesso uma das minhas idéias (entre no Google), então talvez o problema não esteja nas idéias.
4

Nos anos 80, a distorção dinâmica do tempo foi o método usado para a correspondência de modelos no reconhecimento de fala. O objetivo era tentar combinar séries temporais de fala analisada com modelos armazenados, geralmente de palavras inteiras. A dificuldade é que as pessoas falam em taxas diferentes. O DTW foi usado para registrar o padrão desconhecido no modelo. Foi chamado de "folha de borracha" correspondente. Basicamente, você pesquisa algumas possibilidades restritas de como a série temporal pode ser estendida localmente para otimizar o ajuste global. Essa abordagem mostrou ser praticamente a mesma coisa que os modelos ocultos de Markov.

Mike Allerhand
fonte
4

Primeiro, você diz "métrica dinâmica de distorção do tempo"; no entanto, o DTW é uma medida de distância, mas não uma métrica (não obedece à desigualdade triangular).

O artigo [a] compara o DTW a 12 alternativas em 43 conjuntos de dados, o DTW realmente funciona muito bem na maioria dos problemas.

Se você quiser saber mais sobre o DTW, poderá ver o tutorial de Keoghs http://www.cs.ucr.edu/~eamonn/Keogh_Time_Series_CDrom.zip (aviso de 500 meg)

O passe é peggy.

Há também um tutorial sobre SAX http://www.cs.ucr.edu/~eamonn/SIGKDD_2007.ppt

[a] Xiaoyue Wang, Hui Ding, Goce Trajcevski, Peter Scheuermann, Eamonn J. Keogh: comparação experimental de métodos de representação e medidas de distância para dados de séries temporais CoRR abs / 1012.2789: (2010)

Eamonn Keogh
fonte
+1 Muito obrigado pela sua resposta. Fiz correções na minha pergunta. Até agora, eu entendo que você é pioneira em séries temporais. Seria ótimo se você tivesse algumas sugestões sobre o meu caso específico, que eu coloquei em um dos comentários: Os dados de séries temporais que tenho são de uma rede interna do tipo twitter e a própria série representa o número de mensagens geradas em um determinado tema. Quero encontrar outros tópicos com uma linha do tempo semelhante à fornecida. Obrigado mais uma vez pelo seu tempo.
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