ggplot2: annotated horizontal lines

 my.value = 0.65
 qplot(1,1)+geom_hline(v=0)+
	geom_text(mapping=aes(x=1,y=0),label=paste(my.value),vjust=-1)

Hello,

I'm using geom_hline to add a minimum line to my plot (representing
the best solution found so far by a search algorithm). I'd like to
annotate this line with it's numerical value to save trying to read it
off the graph, but I can't see a clear way to do this - any ideas?

(Alternatively, if this is against the spirit of the grammar of
graphics, is there a better way to represent the information?)

Cheers,
dave


--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

What's wrong with geom_text?

my.value = 0.65
qplot(1,1)+geom_hline(v=0)+
	geom_text(mapping=aes(x=1,y=0),label=paste(my.value),vjust=-1)

baptiste

On 3 Mar 2009, at 18:10, Dave Murray-Rust wrote:

Hello,

I'm using geom_hline to add a minimum line to my plot (representing
the best solution found so far by a search algorithm). I'd like to
annotate this line with it's numerical value to save trying to read  
it
off the graph, but I can't see a clear way to do this - any ideas?

(Alternatively, if this is against the spirit of the grammar of
graphics, is there a better way to represent the information?)

Cheers,
dave


--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

On 3 Mar 2009, at 18:41, baptiste auguie wrote:

What's wrong with geom_text?

my.value = 0.65
qplot(1,1)+geom_hline(v=0)+
    geom_text(mapping=aes(x=1,y=0),label=paste(my.value),vjust=-1)

Well, firstly I hadn't thought to use it. Ooops.

Secondly, I can't make it just do a single value - it seems to want a
value for every point in the dataset, e.g.:

qplot( wt, mpg, data=mtcars ) +

geom_text(mapping=aes(x=1,y=0,label=paste("0.5"),vjust=-1))
Error in data.frame(..., check.names = FALSE) :
  arguments imply differing number of rows: 1, 32

Cheers,
dave

baptiste

On 3 Mar 2009, at 18:10, Dave Murray-Rust wrote:

Hello,

I'm using geom_hline to add a minimum line to my plot (representing
the best solution found so far by a search algorithm). I'd like to
annotate this line with it's numerical value to save trying to read
it
off the graph, but I can't see a clear way to do this - any ideas?

(Alternatively, if this is against the spirit of the grammar of
graphics, is there a better way to represent the information?)

Cheers,
dave


--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

On 3 Mar 2009, at 18:41, baptiste auguie wrote:

What's wrong with geom_text?

my.value = 0.65
qplot(1,1)+geom_hline(v=0)+
    geom_text(mapping=aes(x=1,y=0),label=paste(my.value),vjust=-1)

Well, firstly I hadn't thought to use it. Ooops.

Secondly, I can't make it just do a single value - it seems to want a
value for every point in the dataset, e.g.:

qplot( wt, mpg, data=mtcars ) +

geom_text(mapping=aes(x=1,y=0,label=paste("0.5"),vjust=-1))
Error in data.frame(..., check.names = FALSE) :
  arguments imply differing number of rows: 1, 32

Cheers,
dave

baptiste

On 3 Mar 2009, at 18:10, Dave Murray-Rust wrote:

Hello,

I'm using geom_hline to add a minimum line to my plot (representing
the best solution found so far by a search algorithm). I'd like to
annotate this line with it's numerical value to save trying to read
it
off the graph, but I can't see a clear way to do this - any ideas?

(Alternatively, if this is against the spirit of the grammar of
graphics, is there a better way to represent the information?)

Cheers,
dave


--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

Dear Dave,

Another option would be to manually create the breaks of your plot.

library(ggplot2)
myBreaks <- sort(c(pretty(mtcars$mpg), min(mtcars$mpg)))
ggplot(aes(x = wt, y = mpg), data = mtcars) + geom_point() +  
geom_hline(yintercept = min(mtcars$mpg)) + scale_y_continuous(breaks  
= myBreaks)

HTH,

Thierry


----------------------------------------------------------------------------
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for  
Nature and Forest
Cel biometrie, methodologie en kwaliteitszorg / Section biometrics,  
methodology and quality assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium
tel. + 32 54/436 185
Thierry.Onkelinx at inbo.be
www.inbo.be

To call in the statistician after the experiment is done may be no  
more than asking him to perform a post-mortem examination: he may be  
able to say what the experiment died of.
~ Sir Ronald Aylmer Fisher

The plural of anecdote is not data.
~ Roger Brinner

The combination of some data and an aching desire for an answer does  
not ensure that a reasonable answer can be extracted from a given  
body of data.
~ John Tukey

-----Oorspronkelijk bericht-----
Van: r-help-bounces at r-project.org [mailto:r-help-bounces at r- 
project.org] Namens baptiste auguie
Verzonden: dinsdag 3 maart 2009 21:50
Aan: Dave Murray-Rust
CC: R Help
Onderwerp: Re: [R] ggplot2: annotated horizontal lines

I see your problem (although label should be outside the mapping in
your case, i think).

A possible workaround is to provide some dummy data, as the default
NULL doesn't seem to work,

 qplot( wt, mpg, data=mtcars ) +
 geom_text(data=data.frame(x=0,y=0),mapping=aes(x=1,y=0),label="test")

I'm sure Hadley will come up with a better explanation.

Best,

baptiste

On 3 Mar 2009, at 19:51, Dave Murray-Rust wrote:

On 3 Mar 2009, at 18:41, baptiste auguie wrote:

What's wrong with geom_text?

my.value = 0.65
qplot(1,1)+geom_hline(v=0)+
   geom_text(mapping=aes(x=1,y=0),label=paste(my.value),vjust=-1)

Well, firstly I hadn't thought to use it. Ooops.

Secondly, I can't make it just do a single value - it seems to want a
value for every point in the dataset, e.g.:

qplot( wt, mpg, data=mtcars ) +

geom_text(mapping=aes(x=1,y=0,label=paste("0.5"),vjust=-1))
Error in data.frame(..., check.names = FALSE) :
 arguments imply differing number of rows: 1, 32

Cheers,
dave

baptiste

On 3 Mar 2009, at 18:10, Dave Murray-Rust wrote:

Hello,

I'm using geom_hline to add a minimum line to my plot (representing
the best solution found so far by a search algorithm). I'd like to
annotate this line with it's numerical value to save trying to read
it
off the graph, but I can't see a clear way to do this - any ideas?

(Alternatively, if this is against the spirit of the grammar of
graphics, is there a better way to represent the information?)

Cheers,
dave


--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.