Hi Petr, Thank you for the response. I am not familiar with the nls package. I am interested in obtaining a function to represent the relationship observed in "dat" over x.seq (days) so that I can calculate a minimum and maximum of the function.
In the example below, it seems like you are using a data frame, but I tried to create the data frame from x.seq and dat: dat.df <- data.frame(x.seq, dat) However, I got the following error: Error in nls(dat ~ SSlogis(x, Asym, xmid, scal), data = dat.df, start = list(Asym = 90, : parameters without starting value in 'data': x Thank you for your assistance, Katrina On Thu, Aug 4, 2011 at 11:14 PM, Petr PIKAL <petr.pi...@precheza.cz> wrote: > Hi > > Are you sure about sine fit? Seems to me that logistics would be better > > fit<-nls(dat ~ SSlogis(x, Asym, xmid,scal), data = dat.df, start = > list(Asym=90, xmid = 75, scal = -6)) > plot(dat.df) > lines(dat.df$x[complete.cases(dat.df)], predict(fit)) > > Regards > Petr > > > > > > > Hello, I'm trying to generate a sine wave in R to fit my observations > using > > the general formula: > > > > y=a*sin(b[x+h*pi)]+k > > > > where a = amplitude, b=period, h=phase shift, and k=vertical shift > > > > I want to use following translation to bring the sine function up onto > the > > y-axis to range from 0-1, and this will place the wave on the x-axis > from > > 0-pi/2. > > > > y=1/2sin(2[x+ 1/4*pi]) + 1/2 > > > > Additionally, I need to spread this along a x-axis that spans 1-153 > (days). > > > > Can anyone help with this? I seem to be able to use the curve function > fine, > > but entering the translations doesn't seem to provide an answer. > > > > Here is an example of the data set I am trying to 'match' using this > > function. > > > > dat <- > > > c(75.44855206,NA,NA,NA,82.70745342,82.5335019,88.56617647,80.00128866,94. > > 15418227,86.63987539,93.91052952,74.10612245,86.62289562,90. > > 47961047,NA,NA,82.45320197,72.14371257,NA,71.44104803,72.59742896,68. > > 36363636,NA,NA,61,NA,NA,71.26502909,NA,85.93333333,84.34248284,79. > > 00522193,79.64223058,97.2074017,88.43700548,96.40413877,95.13511869,92. > > 57379057,93.97498475,NA,97.55995131,89.53321146,97.21728545,93.21980198, > > 77.54054054,95.85392575,86.25684723,97.55325624,80.03950617,NA,91. > > 34023128,92.42906574,88.59433962,65.77272727,89.63772455,NA,NA,NA,NA,74. > > 86344239,83.57594937,70.22516556,65.30543319,NA,NA,67.84852294,60. > > 90909091,54.79303797,NA,52.18735363,33.47003155,NA,41.34693878,24. > > 5047043,NA,NA,NA,NA,9.944444444,13.6875,NA,11.90267176,84.14285714,3. > > 781456954,NA,1.432926829,4.26557377,1.823529412,0.444620253,4. > > > 711155378,NA,6.320284698,0.581632653,0.144578313,3.666666667,0,0,0,0,0,NA, > > 0.032947462,0,0,10.54545455,0,NA,0.561007958,0.75,NA,0.048780488,0. > > 74137931,NA,2.023339318,0,0,0,NA,NA,0.156950673,NA,0.283769634,32. > > > 81818182,NA,NA,0,NA,0,0,0,NA,0.212454212,3.120181406,NA,0.011811024,NA,0, > > > 0.120430108,5.928571429,1.75,0.679292929,0.97,NA,0,NA,NA,1,0.38547486,NA, > > 1.460732984,0.007795889,0.05465288,0.004341534) > > plot(dat/100) > > par(new=F) > > x.seq <- seq(100, 0, , 153) > > y <- ??? #*y = 2 sin 2Ä⬠(x - 1/4)* or y ~ a + c*sin(x+b) > > > > However, I can't find a reference for the no place for k. Also, I've > tried a > > lot of different iterations, but can't seem to figure out how to do this > in > > R. > > > > Any thoughts or ideas on this? > > > > Thank you, > > > > Katrina > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > -- Katrina E. Bennett PhD Student University of Alaska Fairbanks International Arctic Research Center 930 Koyukuk Drive, PO Box 757340 Fairbanks, Alaska 99775-7340 907-474-1939 office 907-385-7657 cell kebenn...@alaska.edu Personal Address: UAF, PO Box 752525 Fairbanks, Alaska 99775-2525 bennett.katr...@gmail.com [[alternative HTML version deleted]]
______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
