[R] Problems with "predict" function ii

[Rui Barradas]

Hello,

First of all, your question is about 'predict' but you include graphic 
instructions that have nothing to do with it. They do not hurt, but the 
reproducible example should also be minimal.

Second, whenever you use RNG's, you should start it with set.seed().

Now, I have edited your code and it all works. No errors.
I got it rid of attach/detach and of the graphics.
And added spaces around some bits, such as <-, =, etc.


set.seed(187)    # Make the results reproducible

m <- runif(1,0,1)
m
mres <- m*(seq(1, 12))
mres
ssd <- rexp(1, 1)
ssd
devs <- rep(0, length(mres))
for(i in 1:length(mres)){
     devs[i] <- rnorm(1, 0, ssd)
}
devs
sales <- round((mres+devs)*1000)

ptr <- cbind(1:length(sales), sales, sales, sales)
ptr

sdf <- data.frame(1:nrow(ptr), sales)
colnames(sdf)<-c("monat", "mitte")
sdf

#attach(sdf)
s.lm <- lm(mitte ~ monat, sdf)
s.lm

news <- data.frame(monat = nrow(sdf) + 1)
news

fcs <- predict(s.lm, newdata = news, interval = "predict")
fcs

ptr <- rbind(ptr, c(1 + nrow(ptr), fcs[2], fcs[1], fcs[3]))
ptr

highdf <- data.frame(ptr[, c(1, 4)])
colnames(highdf) <- c("month","sales")
highdf

#detach(sdf)
#attach(highdf)
h.lm <- lm(sales ~ month, highdf)
h.lm
news <- data.frame(month = nrow(ptr) + 1)
news
hcs <- predict(h.lm, newdata = news, interval = "predict")
hcs



On 1/31/2018 5:20 PM, WRAY NICHOLAS via R-help wrote:
> I  have realised that I should have used "detach" before attaching another
> dataframe, but even when I do this it's still giving me lots of lines, rather
> than just one:
> 
> My code:
> 
> 
> m<-runif(1,0,1)
> m
> mres<-m*(seq(1,12))
> mres
> ssd<-rexp(1,1)
> ssd
> devs<-rep(0,length(mres))
> for(i in 1:length(mres)){devs[i]<-rnorm(1,0,ssd)}
> devs
> plot(-10,-10,xlim=c(1,24),ylim=c(0,20000))
> sales<-round((mres+devs)*1000)
> 
> points(sales,pch=19)
> 
> ptr<-cbind(1:length(sales),sales,sales,sales)
> 
> ptr
> sdf<-data.frame(cbind(1:nrow(ptr),sales))
> sdf
> 
> colnames(sdf)<-c(“monat”,“mitte”)
> sdf
> attach(sdf)
> s.lm<-lm(mitte~monat)
> 
> s.lm
> abline(s.lm,lty=2)
> news<-data.frame(monat=nrow(sdf)+1)
> news
> fcs<-predict(s.lm,news,interval=“predict”)
> fcs
> 
> points(1+nrow(ptr),fcs[,1],col=“grey”,pch=19)
> points(1+nrow(ptr),fcs[,2])
> points(1+nrow(ptr),fcs[,3])
> ptr<-rbind(ptr,c(1+nrow(ptr),fcs[2],fcs[1],fcs[3]))
> ptr
> 
> highdf<-data.frame(ptr[,c(1,4)])
> highdf
> colnames(highdf)<-c(“month”,“sales”)
> highdf
> detach(sdf)
> attach(highdf)
> h.lm<-lm(highdf[,2]~highdf[,1])
> h.lm
> abline(h.lm,col="gray",lty=2)
> news<-data.frame(month=nrow(ptr)+1)
> news
> hcs<-predict(h.lm,news,interval=“predict”)
> hcs
> 	[[alternative HTML version deleted]]
> 
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