R help - Dec 2008 - boxplot via plot command

Hi folks,

I've just discovered that the following code leads to boxplot (surprisingly
to me).
Can anybody explain to me why? Is this documented somewhere? I've never 
consider this option before.

x <- rnorm(300)
l <- c(rep("label1",100), rep("label2",50),
rep("label3",150))

df <- data.frame(as.factor(l), x)
plot(df)


Thank you!
Antje

Hi,
Antje <niederlein-rstat <at> yahoo.de>
writes:
> 
> Hi folks,
> 
> I've just discovered that the following code leads to boxplot 
> (surprisingly to me).
> Can anybody explain to me why? Is this documented somewhere? I've never
> consider this option before.
> 
> x <- rnorm(300)
> l <- c(rep("label1",100), rep("label2",50),
rep("label3",150))
> 
> df <- data.frame(as.factor(l), x)
> plot(df)
> 
> Thank you!
> Antje
> 
You can follow this through the various methods.  If you look
at plot.data.frame  

getAnywhere(plot.data.frame)  

You'll see that when the data.frame has only 2 columns, it
calls plot with the first two arguments.  Since the first argument
here is a factor, it dispatches to the plot.factor method

getAnywhere(plot.factor)

from which you'll see that under your circumstances it will call 
boxplot

HTH,

Ken

Antje <niederlein-rstat <at> yahoo.de>
writes:
> I've just discovered that the following code leads to boxplot 
> (surprisingly to me).
> Can anybody explain to me why? Is this documented somewhere? I've never
> consider this option before.
> x <- rnorm(300)
> l <- c(rep("label1",100), rep("label2",50),
rep("label3",150))
> df <- data.frame(as.factor(l), x)
> plot(df)
Just to complete my  response, 
the documentation for plot.data.frame indicates

For a two-column data frame it plots the second column 
against the first by the most appropriate method for 
the first column.


kk

-- 
Ken Knoblauch
Inserm U846
Institut Cellule Souche et Cerveau
D?partement Neurosciences Int?gratives
18 avenue du Doyen L?pine
69500 Bron
France
tel: +33 (0)4 72 91 34 77
fax: +33 (0)4 72 91 34 61
portable: +33 (0)6 84 10 64 10
http://www.sbri.fr

Hi,

thank you both for your response.
I don't want to do anything like this - I just got some code like this from 
someone else and was wondering about the result.
I would have used another approach to create a boxplot like this...

Ciao,
Antje

markleeds at verizon.net schrieb:
>  hi: i'm not well versed in the OO mechanism behind R but you've
created
> a dataframe with one column being factors so,
> when the plot command sees this, there must be code in the plot generic 
> that decided that the best thing to use is a boxplot.
> 
> I'm not sure what you want since you have 3 factors but below is a
guess
> ? I split by the factor and then plot the values seperately
> with the colors denoting the factors ? if it's not what you want, then
i
> would resend your question to the list explaining what you
> do want because there are others on this list that can probably help you 
> more than i can. good luck.
> 
> x <- rnorm(300)
> l <- c(rep("label1",100), rep("label2",50),
rep("label3",150))
> 
> df <- data.frame(l=as.factor(l), x)
> print(df)
> print(str(df))
> 
> temp <- split(df,df$l)
> 
> plot(temp[[1]]$x,ylim=c(min(temp[[1]]$x,temp[[2]]$x,temp[[3]]$x),
> 
> max(temp[[1]]$x,temp[[2]]$x,temp[[3]]$x)),col="green")
> 
> lines(temp[[2]]$x,type="p",col="blue")
> lines(temp[[3]]$x,type="p",col="red")
> 
> 
> 
> On Tue, Dec 2, 2008 at  3:30 AM, Antje wrote:
> 
>> Hi folks,
>>
>> I've just discovered that the following code leads to boxplot 
>> (surprisingly to me).
>> Can anybody explain to me why? Is this documented somewhere? I've 
>> never consider this option before.
>>
>> x <- rnorm(300)
>> l <- c(rep("label1",100), rep("label2",50),
rep("label3",150))
>>
>> df <- data.frame(as.factor(l), x)
>> plot(df)
>>
>>
>> Thank you!
>> Antje
>>
>> ______________________________________________
>> 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.
>