[R] ggplot2: annotated horizontal lines

[Dave Murray-Rust]

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
>>
>>
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>
> _____________________________
>
> 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.