R help - Dec 2009 - "Object is not a matrix" Error

I'm trying to follow this guide here:
http://www.ats.ucla.edu/stat/r/modules/dummy_vars.htm

In which I'm creating categorical variables using the factor function.

I am able to go through the example listed above and have everything work,
however, when I try to input my own numbers, I get an error.  I input the
following:

> hits = read.csv(file.choose())
> attach(hits)
> day.f <- factor(day)
> lm(write ~ (day.f))
lm(write ~ (day.f))

Error in model.frame.default(formula = write ~ (day.f), drop.unused.levels >
TRUE) :
>   object is not a matrix
>
So I import "hits = read.csv(file.choose())" a .csv file, which has
the
columns "visits" and "day" where "visits" is the
number of hits to a
website, and "day" is a number 1-7, for example 1 corresponds to
Sunday and
7 corresponds to Saturday.  I understand that the day variable needs to be a
categorical variable, and I'm trying to use the factor function to do this.
 I would like to be able to run a regression that will correlate the day
with the number of hits.

Any help would be much appreciated.

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Where is the object 'write'?  SHouldn't you be using:

 lm(visits ~ (day.f))


On Sun, Dec 20, 2009 at 5:59 PM, John Paul Telthorst
<jptelthorst@gmail.com>wrote:
> I'm trying to follow this guide here:
> http://www.ats.ucla.edu/stat/r/modules/dummy_vars.htm
>
> In which I'm creating categorical variables using the factor function.
>
> I am able to go through the example listed above and have everything work,
> however, when I try to input my own numbers, I get an error.  I input the
> following:
>
>
> > hits = read.csv(file.choose())
>
> > attach(hits)
>
> > day.f <- factor(day)
>
> > lm(write ~ (day.f))
>
> lm(write ~ (day.f))
>
> Error in model.frame.default(formula = write ~ (day.f), drop.unused.levels
> > > TRUE) :
> >   object is not a matrix
> >
>
> So I import "hits = read.csv(file.choose())" a .csv file, which
has the
> columns "visits" and "day" where "visits" is
the number of hits to a
> website, and "day" is a number 1-7, for example 1 corresponds to
Sunday and
> 7 corresponds to Saturday.  I understand that the day variable needs to be
> a
> categorical variable, and I'm trying to use the factor function to do
this.
>  I would like to be able to run a regression that will correlate the day
> with the number of hits.
>
> Any help would be much appreciated.
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@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<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?

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