R help - Jul 2009 - predict

I have found a regression model, and i would like to predict value in
different points. I have tried to use predict function but it doesn't work.
I have used predict function like this:

newdata<-seq(from=0.1, to=0.32,by=0.02)
data<-predict(fm,newdata)

where fm is a regression model. The predict function return me that:

Error in eval(predvars, data, env) :   numeric argument 'envir'
doesn't have
unitary length

where is the error?


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Newdata needs to be a dataframe with the same variable names as the
explanatory variables in your models.

Model <- lm(y ~ x, data = dataset) 
Newdata <- data.frame(x = seq(from=0.1, to=0.32,by=0.02))
Newdata$y <- predict(Model, newdata = Newdata)

HTH,

Thierry

------------------------------------------------------------------------
----
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature
and Forest
Cel biometrie, methodologie en kwaliteitszorg / Section biometrics,
methodology and quality assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium
tel. + 32 54/436 185
Thierry.Onkelinx at inbo.be
www.inbo.be

To call in the statistician after the experiment is done may be no more
than asking him to perform a post-mortem examination: he may be able to
say what the experiment died of.
~ Sir Ronald Aylmer Fisher

The plural of anecdote is not data.
~ Roger Brinner

The combination of some data and an aching desire for an answer does not
ensure that a reasonable answer can be extracted from a given body of
data.
~ John Tukey

-----Oorspronkelijk bericht-----
Van: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
Namens serbring
Verzonden: woensdag 29 juli 2009 15:31
Aan: r-help at r-project.org
Onderwerp: [R] predict


I have found a regression model, and i would like to predict value in
different points. I have tried to use predict function but it doesn't
work.
I have used predict function like this:

newdata<-seq(from=0.1, to=0.32,by=0.02)
data<-predict(fm,newdata)

where fm is a regression model. The predict function return me that:

Error in eval(predvars, data, env) :   numeric argument 'envir'
doesn't
have
unitary length

where is the error?


--
View this message in context:
http://www.nabble.com/predict-tp24719362p24719362.html
Sent from the R help mailing list archive at Nabble.com.

______________________________________________
R-help at r-project.org mailing list
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.

Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver weer 
en binden het INBO onder geen enkel beding, zolang dit bericht niet bevestigd is
door een geldig ondertekend document. The views expressed in  this message 
and any annex are purely those of the writer and may not be regarded as stating 
an official position of INBO, as long as the message is not confirmed by a duly 
signed document.

You need to create the variable names in newdata (which is generally a  
dataframe)  that match those used in constructing fm. Surely there  
must be a worked example that illustrates this on the help page?

On Jul 29, 2009, at 9:30 AM, serbring wrote:
>
> I have found a regression model, and i would like to predict value in
> different points. I have tried to use predict function but it  
> doesn't work.
> I have used predict function like this:
>
> newdata<-seq(from=0.1, to=0.32,by=0.02)
> data<-predict(fm,newdata)
>
> where fm is a regression model. The predict function return me that:
>
> Error in eval(predvars, data, env) :   numeric argument 'envir'  
> doesn't have
> unitary length
>
> where is the error?
Hard to tell what other errors at work might be at work since no  
reproducible example (and not even the original code to construct fm)  
was offered. Please re-read the Posting Guide.

David Winsemius, MD
Heritage Laboratories
West Hartford, CT

Your 'newdata' is a vector.  To us predict() the newdata supplied must
be a data frame, with components having the same names as the predictors used in
the model.  If some of the variables are factors, then the corresponding factors
in the newdata data frame must have the same names and the same levels as the
original factors used in fitting the model *even if* not all levels are needed
for the prediction.

This is a precise sort of area.  You may need to study the help information in a
bit more detail.  predict() does work, if only you use it correctly.


Bill Venables
http://www.cmis.csiro.au/bill.venables/ 


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of serbring
Sent: Wednesday, 29 July 2009 11:31 PM
To: r-help at r-project.org
Subject: [R] predict


I have found a regression model, and i would like to predict value in
different points. I have tried to use predict function but it doesn't work.
I have used predict function like this:

newdata<-seq(from=0.1, to=0.32,by=0.02)
data<-predict(fm,newdata)

where fm is a regression model. The predict function return me that:

Error in eval(predvars, data, env) :   numeric argument 'envir'
doesn't have
unitary length

where is the error?


-- 
View this message in context:
http://www.nabble.com/predict-tp24719362p24719362.html
Sent from the R help mailing list archive at Nabble.com.

______________________________________________
R-help at r-project.org mailing list
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.