Loop Error in R

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Loop Error in R

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#1 by (3 votes)

5

I created this loop:

library(forecast)
a=1
b=60
while(b<=(NROW(tsarroz))){
  janela=dput(tsarroz [a:b])
  serie=ts(janela,freq=6)
  HW=HoltWinters(serie)
  prev=forecast(HW,6)
  result=data.frame(prev$mean)
  a=a+6
  b=b+6
}

It should create a data window, run the HoltWinters function, and then compute forecast . But it seems that it calculates all windows at once, and the function HoltWinters of error:

Warning messages:
1: In HoltWinters(serie) :
  optimization difficulties: ERROR: ABNORMAL_TERMINATION_IN_LNSRCH

Another problem is that in the "result" should be the sum of the calculated forecasts of each window, but only returns the result of the last one.

My data is:

tsarroz
Time Series:
Start = c(1, 1) 
End = c(55, 5) 
Frequency = 6 
  [1]  604  552  580  561  603  751  444  411  375  383  477  649  330  365  336  370  355
 [18]  418  258  355  407  435  615  676  258  355  556  630  636  925  562  498  396  383
 [35]  486  791  435  322  322  410  402  490  340  328  294  323  342  567  418  469  500
 [52]  478  608 1049  556  455  477  378  431  628  362  637  609  581  431  385  362  375
 [69]  417  287  455  556  362  429  561  287  922  863  544  567  715  590  613  782  413
 [86]  375  328  580  556  654  309  331  363  370  422  451  374  316  313  329  558  745
[103]  574  546  596  513  640  966  447  509  466  268  494  749  509  286  410  268  606
[120]  511  236  371  377  401  462  354  468  586  640  613  347  900  741  283  583  463
[137]  465  528  352  568  477  316  479  528  315  331  339  290  348  451  364  336  380
[154]  393  711  826  485  562  579  624  604  734  453  330  307  359  629  685  346  332
[171]  387  328  453  428  360  378  332  335  462  625  532  550  518  528  751  858  568
[188]  423  490  424  450  616  539  409  379  369  356  436  290  348  286  364  455  497
[205]  323  470  523  547  573  817  506  558  535  428  566  594  342  351  585  445  416
[222]  448  315  348  296  351  394  437  392  317  296  287  468  783  508  456  528  593
[239]  618  819  403  525  362  361  605  481  422  341  323  412  352  545  300  299  309
[256]  352  389  558  504  467  520  424  627  796  556  484  424  516  440  473  473  514
[273]  477  430  437  551  575  571  324  430  341  240  472  392  287  430  365  315  465
[290]  470  549  558  509  463  373  363  307  522  452  407  325  437  245  314  294  327
[307]  339  323  388  382  447  490  616  557  542  582  629  778  436  457  382  434  508
[324]  581  436  457  410  398  378

loop while r previous

asked by anonymous 10.10.2018 / 02:58

1 answer

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score 3 · Answer 1

The error message can be resolved with tryCatch . I've made other changes to your code, too. Now the cycle while stores the results of all iterations in the list result , not only the last one.

library(forecast)

a <-  1
b <- 60
result <- list()
inx <- 1
while(b <= NROW(tsarroz)){
  janela <- tsarroz[a:b]
  serie <- ts(janela, freq = 6)
  HW <- tryCatch(HoltWinters(serie),
                 warning = function(w) w
  )
  if(inherits(HW, "warning"))
    result[[inx]] <- HW
  else{
    prev <- forecast(HW, 6)
    result[[inx]] <- prev$mean
  }
  a <- a + 6
  b <- b + 6
  inx <- inx + 1
}

See how many members have the result list.

length(result)
#[1] 45

See the first element, to get an idea of what the list members are like.

result[[1]]
#Time Series:
#Start = c(11, 1) 
#End = c(11, 6) 
#Frequency = 6 
#[1] 342.4086 324.2339 296.7258 342.0511 398.6264 564.9517

Now, see which iterations went well without warnings , and which ones went wrong.

ok <- sapply(result, inherits, "ts")
bons <- result[ok]
length(bons)
#[1] 41

which(!ok)
#[1] 13 24 36 40

The list bons has only those that went well.

Data in dput format

tsarroz <-
structure(c(604, 552, 580, 561, 603, 751, 444, 411, 375, 383, 
477, 649, 330, 365, 336, 370, 355, 418, 258, 355, 407, 435, 615, 
676, 258, 355, 556, 630, 636, 925, 562, 498, 396, 383, 486, 791, 
435, 322, 322, 410, 402, 490, 340, 328, 294, 323, 342, 567, 418, 
469, 500, 478, 608, 1049, 556, 455, 477, 378, 431, 628, 362, 
637, 609, 581, 431, 385, 362, 375, 417, 287, 455, 556, 362, 429, 
561, 287, 922, 863, 544, 567, 715, 590, 613, 782, 413, 375, 328, 
580, 556, 654, 309, 331, 363, 370, 422, 451, 374, 316, 313, 329, 
558, 745, 574, 546, 596, 513, 640, 966, 447, 509, 466, 268, 494, 
749, 509, 286, 410, 268, 606, 511, 236, 371, 377, 401, 462, 354, 
468, 586, 640, 613, 347, 900, 741, 283, 583, 463, 465, 528, 352, 
568, 477, 316, 479, 528, 315, 331, 339, 290, 348, 451, 364, 336, 
380, 393, 711, 826, 485, 562, 579, 624, 604, 734, 453, 330, 307, 
359, 629, 685, 346, 332, 387, 328, 453, 428, 360, 378, 332, 335, 
462, 625, 532, 550, 518, 528, 751, 858, 568, 423, 490, 424, 450, 
616, 539, 409, 379, 369, 356, 436, 290, 348, 286, 364, 455, 497, 
323, 470, 523, 547, 573, 817, 506, 558, 535, 428, 566, 594, 342, 
351, 585, 445, 416, 448, 315, 348, 296, 351, 394, 437, 392, 317, 
296, 287, 468, 783, 508, 456, 528, 593, 618, 819, 403, 525, 362, 
361, 605, 481, 422, 341, 323, 412, 352, 545, 300, 299, 309, 352, 
389, 558, 504, 467, 520, 424, 627, 796, 556, 484, 424, 516, 440, 
473, 473, 514, 477, 430, 437, 551, 575, 571, 324, 430, 341, 240, 
472, 392, 287, 430, 365, 315, 465, 470, 549, 558, 509, 463, 373, 
363, 307, 522, 452, 407, 325, 437, 245, 314, 294, 327, 339, 323, 
388, 382, 447, 490, 616, 557, 542, 582, 629, 778, 436, 457, 382, 
434, 508, 581, 436, 457, 410, 398, 378), .Tsp = c(1, 55.6666666666667, 
6), class = "ts")