Re: [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(0,2))
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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Re: [R] Problems with "predict" function ii

[PIKAL Petr]

Hi

First of all you should not post in HTML.

Thank you for posting the code, however I do not understand wht exactly do you 
mean by that you get many lines. I get only one with your code.

Other answers see in line

-Original Message-
From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of WRAY NICHOLAS 
via R-help
Sent: Wednesday, January 31, 2018 6:20 PM
To: r-help <r-help@r-project.org>
Subject: [R] Problems with "predict" function ii

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:



And you should not use attach, it is hardly ever necessary.

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(0,2))
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)


instead of attach use
s.lm<-lm(mitte~monat, data=sdf)


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<-lm(sales~month, highdf)


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

I get a picture with two lines, black from you first call to the abline, second 
from your second call. What you want to achieve?

Cheers
Petr



[[alternative HTML version deleted]]

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Re: [R] Problems with "predict" function

[Simmering, Jacob E]

Your messages about masking come from attaching your data set to the R session. 
In general, that is bad practice as it leads to confusing code. It is typically 
better to use the “data” argument in things like lm() to accomplish this task. 

As near as I can tell, your second set of predictions is not working because 
your call to lm() directly references vectors from the highdf data frame. If 
you do this:

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

You should see the expected results. Note that here I’m directly referring to 
the variables “sales” and “month” and not using the bracket notation. 

> On Jan 31, 2018, at 11:08 AM, WRAY NICHOLAS via R-help  
> wrote:
> 
> Hello,
> 
> I am synthesising some sales data over a twelve month period, and then trying 
> to
> use the "predict" function, firstly to generate a thirteenth month forecast 
> with
> upper and lower 95% confidence limits.  So far so good
> 
> But what I then want to do is add the upper sales value at the 95th confidence
> limit to the vector of thirteen months and their respective sales to create a
> fourteenth month with a predicted sale and the 95% upper confidence limit for
> this, and so on  The idea being to create a "trumpet" of extreme posistions
> 
> But I keep getting instead of one line of predictions for the fourteenth 
> month,
> a whole set.  What I don't understand is why it works OK with my original
> synthetic set of twelve months, but doesn't like the set of thirteen sales 
> data
> points, even though as far as I can see I'm just repeating the process, albeit
> with a different label  I have tried to use different column labels in case 
> that
> was the problem but it doesn't seem to make any difference
> 
> I am also getting these weird warning messages telling me that things are 
> being
> "masked":
> 
> The following object is masked _by_ .GlobalEnv:
> 
> sales
> 
> The following object is masked from highdf (pos = 4):
> 
> sales
> Etc
> 
> Is it something to do with attaching the various data frames?  I am a bit at 
> sea
> on this and would be thankful for any pointers
> 
> Nick
> 
> 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(0,2))
> 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
> 
> 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]]
> 
> __
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

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Re: [R] Problems with "predict" function ii

[Jeff Newmiller]

This is the kind of thing that leads experienced R users to avoid attach for 
data analysis. Read "The R Inferno".

Use the "data" argument to lm, and the "newdata" argument to predict.lm.
-- 
Sent from my phone. Please excuse my brevity.

On January 31, 2018 9:20:10 AM PST, 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(0,2))
>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]]
>
>__
>R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide
>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.

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[R] Problems with "predict" function ii

[WRAY NICHOLAS via R-help]

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(0,2))
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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[R] Problems with "predict" function

[WRAY NICHOLAS via R-help]

Hello,

I am synthesising some sales data over a twelve month period, and then trying to
use the "predict" function, firstly to generate a thirteenth month forecast with
upper and lower 95% confidence limits.  So far so good

But what I then want to do is add the upper sales value at the 95th confidence
limit to the vector of thirteen months and their respective sales to create a
fourteenth month with a predicted sale and the 95% upper confidence limit for
this, and so on  The idea being to create a "trumpet" of extreme posistions

But I keep getting instead of one line of predictions for the fourteenth month,
a whole set.  What I don't understand is why it works OK with my original
synthetic set of twelve months, but doesn't like the set of thirteen sales data
points, even though as far as I can see I'm just repeating the process, albeit
with a different label  I have tried to use different column labels in case that
was the problem but it doesn't seem to make any difference

I am also getting these weird warning messages telling me that things are being
"masked":

The following object is masked _by_ .GlobalEnv:

sales

The following object is masked from highdf (pos = 4):

sales
Etc

Is it something to do with attaching the various data frames?  I am a bit at sea
on this and would be thankful for any pointers

Nick

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(0,2))
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

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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