新的自启动功能

Question

我正在关注 Pinheiro & Bates 2000 第 345 页。我想拟合一个 nls 模型，并修改了一个 bitt 逻辑模型。我想创建一个自启动功能，但显示错误。当我运行 "logist3P" 错误 "parameter ‘scal’ does not occur in the model formula" 显示。我认为问题是因为我为 "scal" 参数输入了一个公式。如何输入 "scal" 的公式并避免错误？

logistin3P <- function(mCall, LHS, data)
{
  xy <- sortedXyData(mCall[["x"]], LHS, data)
  if(nrow(xy)<3) {stop("Too few distinct input values to fit a logistic")}
  Asym <- max(abs(xy[,"y"]))
  if(Asym !=max(xy[,"y"])) Asym <- -Asym #negative asymptote
  xmid <- NLSstClosestX(xy, 0.5 * Asym)
  scal <- (((log(Asym)+log(Asym*0.75))/ log(Asym*0.75))/((xmid*1.5)-xmid))         
  value <- c(Asym, xmid, scal)
  names(value) <- mCall[c("Asym","xmid","scal")]
  value
}

logist3P <- selfStart(~Asym/(1+exp(- scal(x-xmid))), initial = logistin3P, parameters = c("Asym","xmid","scal"))

Answer 1

我相信您在模型参数中 scal 之后缺少 *：

logist3P <- selfStart(~Asym/(1+exp(- scal*(x-xmid))), initial = logistin3P, parameters = c("Asym","xmid","scal"))

新的自启动功能

New Self-start function

r

function

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