[R] Boxplot questions.

[Petr Pikal]

Hi

HTH
Petr



On 27 Jun 2006 at 4:45, A Ezhil wrote:

Date sent:      	Tue, 27 Jun 2006 04:45:01 -0700 (PDT)
From:           	A Ezhil <ezhil02 at yahoo.com>
To:             	r-help at stat.math.ethz.ch
Subject:        	[R] Boxplot questions.

> Dear all,
> 
> I am having a data for 2 different treatments with
> different time points. So, I used the following code
> to plot the boxplot and also to do anova. 
> 
> T11 <- c(280, 336, 249, 277, 429)
> T12 <- c(400, 397, 285, 407, 313)
> T13 <- c(725, 373, 364, 706, 249)
> 
> T21 <- c(589, 257, 466, 248, 913)
> T22 <- c(519, 424, 512, 298, 907)
> T23 <- c(529, 479, 634, 354, 1015)
> 
> obs <- c(T11, T12, T13, T21, T22, T23)
> treat <- c(rep("T1",15), rep("T2",15))
> time <- c(rep("one",5), rep("two",5), rep("thr",5),  
>           rep("one",5), rep("two",5), rep("thr",5)  
>          )
> 
> table <- data.frame(obs, treat, time)
> boxplot(obs ~ treat*time, data=table)
> 
> I am able to produce a boxplot for the above data. 
> (1) If I want to add a color to T1 and different color
> to T2, what are the options I should use?

 from help page

 border an optional vector of colors for the outlines of the 
boxplots. The values in border are recycled if the length of border 
is less than the number of plots. 

 col if col is non-null it is assumed to contain colors to be used to 
colour the bodies of the box plots. By default they are in the 
background colour. 


 > boxplot(obs ~ treat*time, data=table, border=rep(1:3,each=2))


> (2) my prof. asked me to add '*' above the boxplot, if
> the comparison is significant. How do I add this '*'
> in the boxplot? 

see bxp and try

bbb<- boxplot(.....)

and look at bbb. You can derive positions of boxes from it and put 
any text e.g. asterix according to these positions.

HTH
Petr







> 
> I used: anova(lm(obs ~ treat*time, data=table)) for
> finding significance.
> 
> Any help is greatly appreciated. Thanks in advance.
> 
> Regards,
> Ezhil
> 
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Petr Pikal
petr.pikal at precheza.cz