Hi Maybe I am wrong but it seems to me that it is cumulative data from recent epidemy in some state.
If yes, instead of inventing wheel I would go to canned and proved solution using tools from https://www.repidemicsconsortium.org/ I found useful and enlightening this blog especially first part from February 18th. https://timchurches.github.io/blog/ Cheers Petr > -----Original Message----- > From: R-help <r-help-boun...@r-project.org> On Behalf Of Luigi Marongiu > Sent: Thursday, May 14, 2020 5:12 PM > To: r-help <r-help@r-project.org> > Subject: [R] How to find a split point in a curve? > > Dear all, > I am trying to find a turning point in some data. In the initial phase, the > data increases more or less exponentially (thus it is linear in a nat log > transform), then reaches a plateau. I would like to find the point that > marks the end of the exponential phase. > I understand that the function spline can build a curve; is it possible > with it to find the turning points? I have no idea of how to use spline > though. > Here is a working example. > Thank you > > ``` > Y = c(259, 716, 1404, 2173, 3944, 5403, 7140, 9121, > 11220, 13809, 16634, 19869, 23753, 27447, > 30590, 33975, 36627, 39600, 42067, 44082, > 58190, 63280, 65921, 67929, 69977, 71865, > 73614, 74005, 74894, 75717, 76365, 76579, > 77087, 77493, 77926, 78253, 78680, 79253, > 79455, 79580, 79699, 79838, 79981, 80080, > 80124, 80164, 80183, 80207, 80222, 80230, > 80241, 80261, 80261, 80277, 80290, 80303, > 80337, 80376, 80422, 80461, 80539, 80586, > 80653, 80708, 80762, 80807, 80807, 80886, > 80922, 80957, 80988, 81007, 81037, 81076, > 81108, 81108, 81171, 81213, 81259, 81358, > 81466, 81555, 81601, 81647, 81673, 81998, > 82025, 82041, 82053, 82064, 82094, 82104, > 82110, 82122, 82133, 82136, 82142, 82164, > 82168, 82180, 82181, 82184, 82187, 82188, > 82190, 82192, 82193, 82194) > Y = log(Y) > X = 1:length(Y) > plot(Y ~ X, ylab = "Ln(Y)", xlim=c(0,10, main="zoomed in")) > abline(lm(Y[1:3] ~ X[1:3])) > abline(lm(Y[1:5] ~ X[1:5]), lty=2) > text(7, 6, "After third or fifth point, there is deviance", pos=3) > text(2.5, 10, "Solid line: linear model points 1:3", pos =3) > text(2.5, 9, "Dashed line: linear model points 1:5", pos =3) > plot(Y ~ X, ylab = "Ln(Y)", xlim=c(0,10, main="overall")) > abline(lm(Y[1:3] ~ X[1:3])) > ``` > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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.
______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
