最近仿照混合模型写了一段代码：

logistInit <- function(mCall, LHS, data) {

xy <- sortedXyData(mCall[["x"]], LHS, data)

if(nrow(xy) <3) {

stop("Too few distinct input values to fit a logistic")

}

a <- max(abs(xy[,"y"]))

if (a != max(xy[,"y"])) a <- -a# negative asymptote

b <- NLSstClosestX(xy, 0.5 * a)

value <- c(a, b)

names(value) <- mCall[c("a", "b")]

value

}

logist <- selfStart(logist, initial = logistInit)

class(logist)

#[1] "selfStart"

logist <- selfStart(~ a*dbh^b,

initial = logistInit, parameters = c("a", "b"))

getInitial(total ~ logist(dbh,a, b), riben)

运行到此时出现：

错误于tapply(y, x, mean, na.rm = TRUE) : 参数的长度必需一样

不知哪位高手可以致电一下，不胜感激