R中的自动曲线拟合 [英] Automatic curve fitting in R
问题描述
是否有使用许多简单模型自动拟合曲线的软件包?
我是说简单模型:
Is there any package that automatically fits a curve using many simple models?
By simple models I mean:
- ax + b
- ax ^ 2 + bx + c
- a * log(x)+ b
- a * x ^ n + b
- ax /(1 + bx)
- ax ^ n /(1 + bx ^ n)
- ...
- ax+b
- ax^2+bx+c
- a*log(x) + b
- a*x^n+b
- ax/(1+bx)
- ax^n/(1+bx^n)
- ...
最好是具有两个矢量参数的函数X和Y,并返回带有其SSE的拟合简单模型的列表。
The best would be to have a function that takes two vector parameters X and Y and returns a list of fitted simple models with their SSE.
推荐答案
尝试一下。 rhs
是右侧的字符矢量, x
和 y
是数据。它为每个参数构造公式 fo
,然后提取参数并将每个参数的起始值设置为1。最后,它运行 nls
并返回已排序的SSE,以便结果是通过右侧命名的SSE的向量。如果 verbose = TRUE
(默认情况下),则还会显示每个拟合的输出。
Try this. rhs
is a character vector of right sides and x
and y
are the data. It constructs the formula fo
for each and then extracts the parameters and sets each to 1 for the starting value. Finally it runs nls
and returns the SSEs sorted so that the result is a vector of SSE's named via the right hand sides. If verbose=TRUE
(which it is by default) then it also displays the output from each fit.
sse <- function(rhs, x, y) sort(sapply(rhs, function(rhs, x, y, verbose = TRUE) {
fo <- as.formula(paste("y", rhs, sep = "~"))
nms <- setdiff(all.vars(fo), c("x", "y"))
start <- as.list(setNames(rep(1, length(nms)), nms))
fm <- nls(fo, data.frame(x, y), start = start)
if (verbose) { print(fm); cat("---\n") }
deviance(fm)
}, x = x, y = y))
## test
set.seed(123)
x <- 1:10
y <- rnorm(10, x)
# modify to suit
rhs <- c("a*x+b", "a*x*x+b*x+c")
sse(rhs, x, y)
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