Question

我正在向nls()中输入动态输入，但无法使start参数起作用。看来我不知道该如何喂给正确的对象。我需要正确结构的对象vars来满足start参数。

在此示例中，我的起始值存储在vars中。我尝试过重塑它以及使用as.vector，as.array和as.matrix等对象类弄乱了，但没有成功。

#need this package for acm.disjonctif()
library(ade4)

#get some fake data going for an ad measurement scenario
durta <- data.frame (  
    "impact"=c(150,150,350,50,150,150,  140,160,330,80,130,170)
  , "spend"= c(1000,1200,2300,500,1300,1000,  1900,1200,2000,500,1000,1400)
  , "adtitle"=c("zip","bang","boom","zip","bang","boom",  "zip","bang","boom","zip","bang","boom")
  , "network"=c("NBC","TNT","NBC","TNT","NBC","TNT",  "NBC","TNT","NBC","TNT","NBC","TNT")
  )

#making each element from network and adtitle into its own binary dimension
factors <- acm.disjonctif(durta[,3:4])

#getting rid of pesky byproducts
colnames(factors) <- gsub("network.","",gsub("adtitle.","",colnames(factors)))

#going to feed this to nls
input <- data.frame(cbind("impact"=durta$impact,"spend"=durta$spend,factors))

#also need to send these starting values
vars <- data.frame("var"=as.array(letters)[1:ncol(factors)],"start"=0)

#pasting a dynamic formula based on 'input' using as.formula works fine
#tried a similar solution for the starting values, failed 
fit <-  nls(   
  as.formula(paste(paste("impact ~ spend*(", paste(paste(vars[,1],"*"),noquote(colnames(input[3:ncol(input)])), collapse="+")),")"))
  , data=input
  , algorithm = "port"
  , start = vars
  #, start = c(a=.1,b=.3,c=0.3,d=-.9,e=.2)
  #          ^ this version works
)

如果满足start参数，那么我应该得到这个（轻微）错误：

nlsModel（formula，mf，start，wts，upper）中的错误：初始参数估计时的奇异梯度矩阵

当我将工作的静态代码替换为var时，我得到了：

nls（as.formula（paste（paste（“ impact〜花*（” ,, paste（paste（vars [，： 'data'中没有起始值的参数：e

对于这个人为的例子，我已经在静态版本中添加了一些合理的起始值来处理第一个错误，但是仍然会抛出该错误。随它吧。那不是我的问题。

Answer 1

start必须是命名列表。因此

start = setNames(as.list(vars$start), vars$var)

似乎可以做您想做的事情（获取vars$start中值的向量，将其转换为列表，并使用vars$var的对应元素作为其名称）。

对于它的价值，看起来您可以使用lm(impact/spend ~ ., data=input) ...

如何在nls中动态填充起始值？

1 个答案: