[R] ggplot2: annotated horizontal lines

[ONKELINX, Thierry]

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 

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-----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.
>>>
>>> ______________________________________________
>>> 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.
>>
>> _____________________________
>>
>> Baptiste Auguié
>>
>> School of Physics
>> University of Exeter
>> Stocker Road,
>> Exeter, Devon,
>> EX4 4QL, UK
>>
>> Phone: +44 1392 264187
>>
>> http://newton.ex.ac.uk/research/emag
>> ______________________________
>>
>>
>
>
> --
> The University of Edinburgh is a charitable body, registered in
> Scotland, with registration number SC005336.
>

_____________________________

Baptiste Auguié

School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK

Phone: +44 1392 264187

http://newton.ex.ac.uk/research/emag

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