[R] R-help: beginner question

[Douglas Bates]

"Monica Palaseanu-Lovejoy" <monica.palaseanu-lovejoy at stud.man.ac.uk> writes:

> I am a beginner user of R. I have a trivial question – I am almost 
> ashamed I cannot figure it out does not matter how many times I 
> am reading the help.

> I have a table in .txt format, tab delimited. I can read it with 
> ‘read.delim()’ with no problems.

> Afterwards I would like to use boxplot function to see if there 
> are any outliers in the column 5 of my data called TPAH16.ppm

> In the boxplot help I saw that I have to declare my data with 
> ‘data()’. I am getting errors does not matter how I am calling 
> ‘data()’, only with the name of the table, with 
> data(read.delim()), or in any other way. So in the end I was not 
> able to use boxplot at all.

Yours is a common problem for those starting with R.  The problem is
that the object that you have read, let's call it `df', is in a
tabular form (called a "data frame" in R) and you need to specify a
single column of that table as an argument to the boxplot function.

There are several ways to do this.

- Use the `with' function to indicate the data frame to use

with(df, boxplot(TPAH16.ppm))

- Use both the name of the data frame and the name of the column,
separated by $

boxplot(df$TPAH16.ppm)

- Attach the data frame before creating the boxplot

attach(df)
boxplot(TPAH16.ppm)
detach()


-- 
Douglas Bates                            bates at stat.wisc.edu
Statistics Department                    608/262-2598
University of Wisconsin - Madison        http://www.stat.wisc.edu/~bates/