R help - Mar 2006 - Question about 'lables' & ect.

Hi,

I have a file named:
test_R.txt
aaa  2
bbb  5
ccc  7
sss  3
xxx  8

I want to have a plot:
test<-read.table("test_R.txt",col.name=c("Name","Score"))
par(mfrow=c(1,2))
barplot(test$Score)
name<-test$Name
axis(1,at=1:length(test$Name),labels=paste(name))

Q1, if you try the script above,you will get 5 bars, the axis only shows
"aaa", "ccc","xxx", but where are
"bbb"&"sss"?

Q2, pls have a look this x-axis again, you will find the middle of the bars
are not pointing to the x-axes.

Q3, how can i change the width of the bars? I feel they are too "fat".

Thanks!
Nina

	[[alternative HTML version deleted]]

Try something like:

xp <- barplot(test$Score, space=.5)
axis(1, at=xp, labels=as.character(test$Name))

See ?barplot more more detail.

Andy

From: jia ding
> 
> Hi,
> 
> I have a file named:
> test_R.txt
> aaa  2
> bbb  5
> ccc  7
> sss  3
> xxx  8
> 
> I want to have a plot:
>
test<-read.table("test_R.txt",col.name=c("Name","Score"))
> par(mfrow=c(1,2))
> barplot(test$Score)
> name<-test$Name
> axis(1,at=1:length(test$Name),labels=paste(name))
> 
> Q1, if you try the script above,you will get 5 bars, the axis 
> only shows "aaa", "ccc","xxx", but where are
"bbb"&"sss"?
> 
> Q2, pls have a look this x-axis again, you will find the 
> middle of the bars are not pointing to the x-axes.
> 
> Q3, how can i change the width of the bars? I feel they are too
"fat".
> 
> Thanks!
> Nina
> 
> 	[[alternative HTML version deleted]]
> 
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> 
>

On Wed, 2006-03-15 at 17:54 +0100, jia ding wrote:
> Hi,
> 
> I have a file named:
> test_R.txt
> aaa  2
> bbb  5
> ccc  7
> sss  3
> xxx  8
> 
> I want to have a plot:
>
test<-read.table("test_R.txt",col.name=c("Name","Score"))
> par(mfrow=c(1,2))
It's not clear what the purpose is here, at least in this example. Do
you plan on creating a second plot?
> barplot(test$Score)
> name<-test$Name
> axis(1,at=1:length(test$Name),labels=paste(name))
> 
> Q1, if you try the script above,you will get 5 bars, the axis only shows
> "aaa", "ccc","xxx", but where are
"bbb"&"sss"?
The easiest way to do this is to use the 'names.arg' argument in
barplot():

barplot(test$Score, names.arg = as.character(test$Name))

Note that the 'Name' column in the 'test' data frame will be a
factor by
default, so you need to convert it to a character vector here.
> Q2, pls have a look this x-axis again, you will find the middle of the bars
> are not pointing to the x-axes.
Note that in the Value section of ?barplot, it indicates that barplot()
returns the bar midpoints, which are not at integer values along the x
axis.

You would need to do something like:

mp <- barplot(test$Score)

axis(1, at = mp, labels = as.character(test$Name))

> Q3, how can i change the width of the bars? I feel they are too
"fat".
You can use the 'space' argument:

barplot(test$Score, names.arg = as.character(test$Name), space = 0.5)


See the descriptions of the 'width' and 'space' arguments in
?barplot
for some of the subtleties here.

See ?barplot for more information and further examples.

HTH,

Marc Schwartz