Re: [R] lme, nlsList, nlsList.selfStart

From: Spencer Graves <spencer.graves_at_pdf.com>
Date: Sat 18 Feb 2006 - 05:19:34 EST

Dear Prof. Ripley:

  1. That's great. I seem to recall having problems with something like that when using a commercial *-Plus product not unlike R. Version 6.2 of this other software just produced the following for me:
 > tstDF <- data.frame(a = 1:3)
 > tstDF$b <- 2
 > sapply(tstDF, length)

  a b
  3 1

          From R2.2.1, I get "3 3" for this example, as you noted. Once more, I am doubly in your debt, sir, both for helping to make R what it is today AND for helping to educate me on its capabilities.

          2. Alas, my cerebral cortex produced "Nil pointer reference" in trying to parse your other comment, "Read on in your inbox for the solution." Perhaps in the fullness of time, I shall be enlightened.

	  Thanks again,
	  spencer graves

Prof Brian Ripley wrote:

> On Fri, 17 Feb 2006, Spencer Graves wrote:
> 

>> Have you tried making mydata2$Dose the same length as everything
>> else?
> 
> 
> [<- does that for you: all columns in a data frame must be the same 
> length.  Read on in your inbox for the solution.
> 

>>
>> spencer graves
>>
>> Patrick Giraudoux wrote:
>>
>>> Well, right, Dose was indeed in the global environment and not in the
>>> data.frame. Changing it with
>>>
>>> mydata2$Dose<-100 # the real dose at the beginning of the experiment
>>>
>>> improves the thing in a sense... but I face a new error:
>>>
>>> mymod3<-nlsList(Conc+1 ~ Dose * exp(lKe+lKa-lCl) *
>>> (exp(-exp(lKe)*Tps)-exp(-exp(lKa)*Tps)) /(exp(lKa)-exp(lKe)) | Organ,
>>> data=mydata2,
>>> start= c(lKe=-2.77, lKa=-1.41, lCl=-1.13)
>>> )
>>>
>>> Error in exp(-exp(lKa) * Conc + 1 ~ Tps) :
>>> Non-numeric argument to mathematical function
>>> Error in exp(-exp(lKa) * Conc + 1 ~ Tps) :
>>> Non-numeric argument to mathematical function
>>> Error in exp(-exp(lKa) * Conc + 1 ~ Tps) :
>>> Non-numeric argument to mathematical function
>>>
>>> I have checked the variables in the data.frame with:
>>>
>>> > sapply(mydata2,is.factor)
>>> Tps Conc Organ Dose
>>> FALSE FALSE TRUE FALSE
>>> > sapply(mydata2,is.character)
>>> Tps Conc Organ Dose
>>> FALSE FALSE FALSE FALSE
>>>
>>> So everything looks OK on this side...
>>>
>>> Furthermore, I have still this "old" error intact:
>>>
>>> > mymod4<-nlsList(SSfol,data=mydata2)
>>> Error in eval(expr, envir, enclos) : object "input" not found
>>> Error in eval(expr, envir, enclos) : object "input" not found
>>> Error in eval(expr, envir, enclos) : object "input" not found
>>>
>>>
>>> I am really sorry for calling help and boring everybody on this
>>> likely trivial issue (this looks like asking a community to
>>> participate to debogging line by line, a shame!!!), but I must admit
>>> that I am really lost...
>>>
>>> Thanks for your concern,
>>>
>>> Kind regards,
>>>
>>> Patrick
>>>
>>>
>>> Prof Brian Ripley a écrit :
>>>
>>>> We don't have Dose, and I think that is where the error lies. If
>>>> Dose were part of mydata2, this is likely to work, but otherwise it
>>>> is Dose which has the wrong length.
>>>>
>>>> ?nlsList says
>>>>
>>>> data: a data frame in which to interpret the variables named in
>>>> 'model'.
>>>>
>>>> and it means it: you must get all the variables from there.
>>>>
>>>>
>>>> On Fri, 17 Feb 2006, Patrick Giraudoux wrote:
>>>>
>>>>> Spencer,
>>>>>
>>>>> Thanks for the hint. I did not dare to bore people with the full data
>>>>> set and though that this kind of error may have been trivial and often
>>>>> encountered (so leading to a short answer), even though I did not see
>>>>> related messages on the r-help list. I already did the checks
>>>>> suggested
>>>>> before posting, and was aware of the possible confusion between 1
>>>>> and l
>>>>> (actually the variable names were not given by myself).
>>>>>
>>>>> It seems that the trouble comes when the grouping variable "Organ" is
>>>>> used. The best (?) I can do is to dump the data.frame here below.
>>>>>
>>>>> With this example, one can get exactly the same errors:
>>>>>
>>>>> mymod2<-nls(Conc~Dose * exp(lKe+lKa-lCl) *
>>>>> (exp(-exp(lKe)*Tps)-exp(-exp(lKa)*Tps)) /(exp(lKa)-exp(lKe)),
>>>>> data=mydata2,
>>>>> start= c(lKe=-2.77, lKa=-1.41, lCl=-1.13)
>>>>> )
>>>>>
>>>>> ... works well!!!
>>>>>
>>>>> but we get then:
>>>>>
>>>>> mymod3<-nlsList(Conc~Dose * exp(lKe+lKa-lCl) *
>>>>> (exp(-exp(lKe)*Tps)-exp(-exp(lKa)*Tps)) /(exp(lKa)-exp(lKe)) | Organ,
>>>>> data=mydata2,
>>>>> start= c(lKe=-2.77, lKa=-1.41, lCl=-1.13)
>>>>> )
>>>>> Error in model.frame(formula, rownames, variables, varnames, extras,
>>>>> extranames, :
>>>>> variable lengths differ
>>>>> Error in model.frame(formula, rownames, variables, varnames, extras,
>>>>> extranames, :
>>>>> variable lengths differ
>>>>> Error in model.frame(formula, rownames, variables, varnames, extras,
>>>>> extranames, :
>>>>> variable lengths differ
>>>>>
>>>>>
>>>>> > mymod4<-nlsList(SSfol,data=mydata2)
>>>>> Error in eval(expr, envir, enclos) : object "input" not found
>>>>> Error in eval(expr, envir, enclos) : object "input" not found
>>>>> Error in eval(expr, envir, enclos) : object "input" not found
>>>>>
>>>>>
>>>>> Sorry and apologise for the inconvenience met,
>>>>>
>>>>> Kind regards,
>>>>>
>>>>> Patrick
>>>>>
>>>>>
>>>>>
>>>>> # data.frame just to copy and past into R
>>>>>
>>>>> "mydata2" <-
>>>>> structure(list(Tps = c(1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3,
>>>>> 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6,
>>>>> 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 9, 9, 9,
>>>>> 9, 9, 9, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 14,
>>>>> 14, 14, 14, 14, 17, 17, 17, 17, 17, 20, 20, 20, 20, 25, 28, 29,
>>>>> 50, 50, 50, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136,
>>>>> 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4,
>>>>> 4, 4, 4, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7,
>>>>> 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10,
>>>>> 10, 10, 11, 11, 11, 11, 11, 11, 14, 14, 14, 14, 14, 17, 17, 17,
>>>>> 17, 17, 20, 20, 20, 20, 25, 28, 29, 50, 50, 50, 136, 136, 136,
>>>>> 136, 136, 136, 136, 136, 136, 136, 1, 1, 1, 1, 1, 1, 2, 2, 2,
>>>>> 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5,
>>>>> 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8,
>>>>> 8, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11,
>>>>> 11, 11, 14, 14, 14, 14, 14, 17, 17, 17, 17, 17, 20, 20, 20, 20,
>>>>> 25, 28, 29, 50, 50, 50, 136, 136, 136, 136, 136, 136, 136, 136,
>>>>> 136, 136), Conc = c(0, 0, 0, 0, 0, 0, 0, 0.807852503274902,
>>>>> 0.204371494701886,
>>>>> 0.579222129993907, 0.989062273721619, 0, 1.11728297897571,
>>>>> 1.41057428121324,
>>>>> 0.888883702851307, 1.259907624008, 1.45753269675829, 1.07077516747401,
>>>>> 0.843279379, 0, 0.763110069196737, 1.11297791434297, 1.10087763997637,
>>>>> 0.946929594501016, 1.33112168, 0.654041755, 0.694167499, 1.289548703,
>>>>> 1.117139864, 0.807196192, 0.720221376552025, 0.560082823, 0.476583438,
>>>>> 2.590855204, 0.51510972, 1.072946887, 0.537999938614396,
>>>>> 0.886684225905255,
>>>>> 0.630178116793598, 1.31534758842196, 1.33333958571746,
>>>>> 0.922032210748255,
>>>>> 0.429930193046174, 1.35881467717335, 0.790045927902363,
>>>>> 1.22484702570724,
>>>>> 0.808104508207897, 1.31185966817903, 1.51837686425553,
>>>>> 1.74105163638734,
>>>>> 1.80365598487402, 1.13240352674377, 1.50086243061644,
>>>>> 2.06355364280445,
>>>>> 0.439350890906039, 1.54692793444949, 1.78758216051046,
>>>>> 1.09043400023239,
>>>>> 0.811328376840514, 0.459192443530981, 0.695333473157298,
>>>>> 0.387995007681174,
>>>>> 0.784627063444921, 1.02282256375842, 0.382687104107726,
>>>>> 0.554290634950242,
>>>>> 0.130420456296453, 0.324194753224919, 0.31106140274139,
>>>>> 0.513473505828888,
>>>>> 0.878620320248701, 1.18404358659996, 0.136926837896477, 0, 0,
>>>>> 0.835588760032974, 0.558617235576616, 1.21002805866839,
>>>>> 0.769381068031404,
>>>>> 1.04514254228094, 0.373251847173678, 0.389005898972802,
>>>>> 0.183141006154896,
>>>>> 0.223596336820146, 0.315526423315647, 0.0930349732768131,
>>>>> 0.169959185212759,
>>>>> 0.161878841748425, 0, 0.0483041009105874, 0, 0, 0, 0.0777005553478052,
>>>>> 0, 0.153175826795441, 0.0428171049833677, 0, 0, 0, 0, 0, 0, 0,
>>>>> 0, 0, 0, 26.564295705327, 5.5893744508169, 7.22612934071834,
>>>>> 36.6563989567777, 0, 28.8967184437329, 28.4030370337251,
>>>>> 28.0886043901352,
>>>>> 26.1230935842208, 28.8895673910072, 42.6814210131968,
>>>>> 32.3555695551062,
>>>>> 0.76883326657205, 34.6159136622156, 38.329242204291, 56.4476583636484,
>>>>> 26.6249506083603, 31.3001451026823, 23.7339071829084,
>>>>> 23.3702284599355,
>>>>> 36.669903715038, 44.7377244306005, 31.2079335923023, 32.8613384312272,
>>>>> 29.4259634309146, 45.6112405959009, 48.1231689836687,
>>>>> 55.0037961570027,
>>>>> 32.9822316456421, 20.0382768189682, 26.0986380308655,
>>>>> 28.8915584506145,
>>>>> 28.7949023823068, 30.0278417498425, 58.8089779973569,
>>>>> 20.3602570111197,
>>>>> 29.6269605259023, 28.4404986724604, 30.2165182590977,
>>>>> 19.9204461889074,
>>>>> 31.1019196559556, 30.3847467747055, 36.8726911479995,
>>>>> 51.0618036275519,
>>>>> 23.5408013442579, 36.6948355347593, 27.4753860809429,
>>>>> 24.1341667099646,
>>>>> 27.5411488989643, 35.9021799354022, 19.7417897046158,
>>>>> 31.1403887303244,
>>>>> 46.1743622734049, 34.8235854891765, 22.1714704189293,
>>>>> 33.6805966894274,
>>>>> 35.2814908686112, 42.9767437212852, 38.1264997164547, 5.3651357974451,
>>>>> 42.8990434918385, 25.4908883698364, 25.99649502, 36.4958105490917,
>>>>> 40.8004126550705, 5.36867162116895, 0.00898476265269363, 0,
>>>>> 27.6810997945798,
>>>>> 28.7918300045713, 45.7577183830352, 35.9276318604787,
>>>>> 34.9717618087238,
>>>>> 29.620354272564, 24.6537513599869, 13.5363982464958, 25.8289073574818,
>>>>> 12.0090406245759, 4.753436805, 11.849214652228, 8.41410147611612,
>>>>> 0, 1.80855352862552, 1.1987530031681, 1.01148025243171,
>>>>> 0.495675369574172,
>>>>> 1.62701127228732, 0, 16.6288242287241, 1.23656061354912,
>>>>> 0.323708776035328,
>>>>> 0, 0.566916625204436, 0, 0, 0, 0, 0, 0, 0, 2.53578781871283,
>>>>> 3.50083667130797, 0, 0.98049572179098, 0, 3.57129673217304,
>>>>> 2.77298867949388,
>>>>> 2.12302645642669, 4.11923869203499, 4.69069462193674, 2.8698666062651,
>>>>> 2.05079837323067, 0.0602771574448942, 5.96454350250626,
>>>>> 2.26267114439802,
>>>>> 3.06911285674854, 2.04233129537404, 2.62181873844029,
>>>>> 1.51813653072598,
>>>>> 1.46193772981073, 2.69864635755833, 3.44016493913122,
>>>>> 2.50834832469627,
>>>>> 3.48170744166168, 1.00637581555435, 1.67065398473081,
>>>>> 4.18855363095027,
>>>>> 3.39649762611015, 1.72804613460423, 1.40053679329531,
>>>>> 2.37032387724109,
>>>>> 3.19332545080983, 2.49474373894248, 2.17800931288708, 2.7601484443213,
>>>>> 0.91266104095844, 1.93485048639199, 1.19692593420788,
>>>>> 1.79537330666258,
>>>>> 2.14020930767983, 3.0122526724942, 2.81112226980754, 3.54890724398174,
>>>>> 3.01022926452999, 2.38263226710738, 3.53569238341869,
>>>>> 3.47869329713911,
>>>>> 0.679333339820719, 2.4764260756438, 3.82615100065366,
>>>>> 2.20449890383871,
>>>>> 1.371303113329, 1.2427787019995, 1.73319133880954, 0.391268883238408,
>>>>> 1.73610193837913, 2.68494324646718, 1.77065393606844,
>>>>> 1.45079980147062,
>>>>> 0.763775702906329, 0.98566725668627, 0.37838763208699,
>>>>> 0.841811919286804,
>>>>> 1.46436462204795, 1.98409602726, 0.507005887891038, 0.465515668274195,
>>>>> 0, 1.873365675227, 1.69023864630648, 2.65530855919137,
>>>>> 2.34392199908302,
>>>>> 1.61917643594837, 1.05165934333345, 0.564642823436471,
>>>>> 0.121621029620328,
>>>>> 0.515007625737071, 0.524345809084086, 0.130898614090571,
>>>>> 0.332427740242623,
>>>>> 0.110214989555118, 0, 0.128642193589, 0.119407067173878,
>>>>> 0.128926224027295,
>>>>> 0.0622331866694357, 0.215645168287442, 0, 0.859343941945178,
>>>>> 0.0500810300696456, 0, 0, 0.0628746592609754), Organ =
>>>>> structure(as.integer(c(1,
>>>>> 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
>>>>> 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
>>>>> 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
>>>>> 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
>>>>> 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 3, 3, 3, 3,
>>>>> 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
>>>>> 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
>>>>> 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
>>>>> 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
>>>>> 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
>>>>> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
>>>>> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
>>>>> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
>>>>> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
>>>>> 2, 2, 2, 2, 2)), .Label = c("Carc", "TD", "Foie"), class =
>>>>> c("ordered",
>>>>> "factor"))), .Names = c("Tps", "Conc", "Organ"), row.names = c("1",
>>>>> "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13",
>>>>> "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24",
>>>>> "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35",
>>>>> "36", "37", "38", "39", "40", "41", "42", "43", "44", "45", "46",
>>>>> "47", "48", "49", "50", "51", "52", "53", "54", "55", "56", "57",
>>>>> "58", "59", "60", "61", "62", "63", "64", "65", "66", "67", "68",
>>>>> "69", "70", "71", "72", "73", "74", "75", "76", "77", "78", "79",
>>>>> "80", "81", "82", "83", "84", "85", "86", "87", "88", "89", "90",
>>>>> "91", "92", "93", "94", "95", "96", "97", "98", "99", "100",
>>>>> "101", "102", "103", "104", "105", "106", "107", "108", "109",
>>>>> "110", "111", "112", "113", "114", "115", "116", "117", "118",
>>>>> "119", "120", "121", "122", "123", "124", "125", "126", "127",
>>>>> "128", "129", "130", "131", "132", "133", "134", "135", "136",
>>>>> "137", "138", "139", "140", "141", "142", "143", "144", "145",
>>>>> "146", "147", "148", "149", "150", "151", "152", "153", "154",
>>>>> "155", "156", "157", "158", "159", "160", "161", "162", "163",
>>>>> "164", "165", "166", "167", "168", "169", "170", "171", "172",
>>>>> "173", "174", "175", "176", "177", "178", "179", "180", "181",
>>>>> "182", "183", "184", "185", "186", "187", "188", "189", "190",
>>>>> "191", "192", "193", "194", "195", "196", "197", "198", "199",
>>>>> "200", "201", "202", "203", "204", "205", "206", "207", "208",
>>>>> "209", "210", "211", "212", "213", "214", "215", "216", "217",
>>>>> "218", "219", "220", "221", "222", "223", "224", "225", "226",
>>>>> "227", "228", "229", "230", "231", "232", "233", "234", "235",
>>>>> "236", "237", "238", "239", "240", "241", "242", "243", "244",
>>>>> "245", "246", "247", "248", "249", "250", "251", "252", "253",
>>>>> "254", "255", "256", "257", "258", "259", "260", "261", "262",
>>>>> "263", "264", "265", "266", "267", "268", "269", "270", "271",
>>>>> "272", "273", "274", "275", "276", "277", "278", "279", "280",
>>>>> "281", "282", "283", "284", "285", "286", "287", "288", "289",
>>>>> "290", "291", "292", "293", "294", "295", "296", "297", "298",
>>>>> "299", "300"), class = c("nfnGroupedData", "nfGroupedData",
>>>>> "groupedData",
>>>>> "data.frame"), formula = quote(Conc ~ Tps | Organ), FUN = function (x)
>>>>> max(x, na.rm = TRUE), order.groups = TRUE)
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Spencer Graves a écrit :
>>>>>
>>>>>> Regarding the following:
>>>>>>
>>>>>>> mymod3<-nlsList(Conc~Dose * exp(lKe+lKa-lCl) *
>>>>>>> (exp(-exp(lKe)*Tps)-exp(-exp(lKa)*Tps)) /(exp(lKa)-exp(lKe)),
>>>>>>> data=mydata,
>>>>>>> start= c(lKe=-2.77, lKa=-1.41, lCl=-1.13)
>>>>>>> Error in model.frame(formula, rownames, variables, varnames, extras,
>>>>>>> extranames, :
>>>>>>> variable lengths differ
>>>>>>
>>>>>>
>>>>>>
>>>>>> This example is NOT self contained and is entirely too
>>>>>> complicated for me to try to replicate it myself in a reasonable
>>>>>> period of time. I will therefore ask one short question: Are all
>>>>>> the
>>>>>> variable names in the "nlsList" call either columns of "mydata" or
>>>>>> parameters to be estimated and therefore spelled out in "start"?
>>>>>> If I
>>>>>> were you, I'd check this all very carefully, being especially careful
>>>>>> about the distinction between "lCl" and "lC1", in particular.
>>>>>>
>>>>>> If you'd like further help with this, I suggest you try to find
>>>>>> the simplest possible example that generates problem you don't
>>>>>> understand, then try to recast that example into one that is
>>>>>> completely self contained, either a data set in the standard R or
>>>>>> nlme
>>>>>> distribution or numbers that one can generate with a very few lines
>>>>>> of code. If you use random numbers, please "set.seed", to increase
>>>>>> your confidence that someone else will see what you see. (And please
>>>>>> review the posting guide! "www.R-project.org/posting-guide.html".
>>>>>> Doing so may increase your chances of getting more useful information
>>>>>> more quickly.)
>>>>>>
>>>>>> spencer graves
>>>>>>
>>>>>> Patrick Giraudoux wrote:
>>>>>>
>>>>>>> Dear listers,
>>>>>>>
>>>>>>> I am trying to fit a model using nlsList() using alternately a
>>>>>>> SSfol() selfstart function or its developped equivalent formulae.
>>>>>>>
>>>>>>> This preliminary trial works well
>>>>>>>
>>>>>>> mydata<-groupedData(Conc~Tps|Organ,data=mydata)
>>>>>>> mymod1<-nls(Conc~SSfol(Dose,Tps,lKe,lKa,lCl),data=mydata)
>>>>>>>
>>>>>>> as well as a developped form:
>>>>>>>
>>>>>>> mymod2<-nls(Conc~Dose * exp(lKe+lKa-lCl) *
>>>>>>> (exp(-exp(lKe)*Tps)-exp(-exp(lKa)*Tps)) /(exp(lKa)-exp(lKe)),
>>>>>>> data=mydata,
>>>>>>> start= c(lKe=-2.77, lKa=-1.41, lCl=-1.13)
>>>>>>> )
>>>>>>>
>>>>>>> However when trying to fit the model with nlsList, I get:
>>>>>>>
>>>>>>> mymod3<-nlsList(Conc~Dose * exp(lKe+lKa-lCl) *
>>>>>>> (exp(-exp(lKe)*Tps)-exp(-exp(lKa)*Tps)) /(exp(lKa)-exp(lKe)),
>>>>>>> data=mydata,
>>>>>>> start= c(lKe=-2.77, lKa=-1.41, lCl=-1.13)
>>>>>>> )
>>>>>>> Error in model.frame(formula, rownames, variables, varnames, extras,
>>>>>>> extranames, :
>>>>>>> variable lengths differ
>>>>>>> Error in model.frame(formula, rownames, variables, varnames, extras,
>>>>>>> extranames, :
>>>>>>> variable lengths differ
>>>>>>> Error in model.frame(formula, rownames, variables, varnames, extras,
>>>>>>> extranames, :
>>>>>>> variable lengths differ
>>>>>>>
>>>>>>> Or specifying the grouping factor explicitely:
>>>>>>>
>>>>>>> mymod3<-nlsList(Conc~Dose * exp(lKe+lKa-lCl) *
>>>>>>> (exp(-exp(lKe)*Tps)-exp(-exp(lKa)*Tps)) /(exp(lKa)-exp(lKe))|Organ,
>>>>>>> data=mydata,
>>>>>>> start= c(lKe=-2.77, lKa=-1.41, lCl=-1.13)
>>>>>>> )
>>>>>>>
>>>>>>> Error in model.frame(formula, rownames, variables, varnames, extras,
>>>>>>> extranames, :
>>>>>>> variable lengths differ
>>>>>>> Error in model.frame(formula, rownames, variables, varnames, extras,
>>>>>>> extranames, :
>>>>>>> variable lengths differ
>>>>>>> Error in model.frame(formula, rownames, variables, varnames, extras,
>>>>>>> extranames, :
>>>>>>> variable lengths differ
>>>>>>>
>>>>>>>
>>>>>>> I cannot find out why the grouping factor cannot be used (it has the
>>>>>>> same length as the other variables...)
>>>>>>>
>>>>>>> Another strange thing occurs: in the example given in the help of
>>>>>>> nlsList.selfstart, the following command works well:
>>>>>>>
>>>>>>> fm1 <- nlsList(SSasympOff, CO2)
>>>>>>>
>>>>>>> However its seemingly equivalent applied to the case above fails:
>>>>>>>
>>>>>>> mymod4<-nlsList(SSfol,data=mydata)
>>>>>>> Error in eval(expr, envir, enclos) : object "input" not found
>>>>>>> Error in eval(expr, envir, enclos) : object "input" not found
>>>>>>> Error in eval(expr, envir, enclos) : object "input" not found
>>>>>>>
>>>>>>>
>>>>>>> Any hint/suggestion appreciated.
>>>>>>>
>>>>>>> Kind regards,
>>>>>>>
>>>>>>> Patrick Giraudoux
>>>>>>>
>>>>>>> ______________________________________________
>>>>>>> R-help@stat.math.ethz.ch mailing list
>>>>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>>>>> PLEASE do read the posting guide!
>>>>>>> http://www.R-project.org/posting-guide.html
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>> ______________________________________________
>>>>> R-help@stat.math.ethz.ch mailing list
>>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>>> PLEASE do read the posting guide!
>>>>> http://www.R-project.org/posting-guide.html
>>>>>
>>>>
>>>
>>
>>
>

R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sat Feb 18 05:31:05 2006

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