[R] Adding lines in ggplot2

[ONKELINX, Thierry]

Dear Eduardo,

This a solution that you seem to want

n <- 1:10
x <- sqrt(n)
y <- log(n)
qplot(n, x, geom="line", colour="darkgreen") + geom_line(data =
data.frame(n , x = y), colour="red")

But please compare it with the solution (code + result) below.
Formatting the data.frame might be a bit more work, but formatting your
graph is much easier.

n <- 1:10
dataset <- 
	rbind(
		data.frame(Number = n, Function = "sqrt", Result =
sqrt(n)),
		data.frame(Number = n, Function = "log", Result =
log(n))
)
#Using the default colours
ggplot(dataset, aes(x = Number, y = Result, colour = Function)) +
geom_line()
#Using user-specified colours
ggplot(dataset, aes(x = Number, y = Result, colour = Function)) +
geom_line() + scale_colour_manual(values = c(sqrt = "darkgreen", log =
"red"))

Think about the gain when you want to display much more than 2 lines...

dataset <- expand.grid(Number = n, Power = seq(0, 2, length = 21))
dataset$Result <- dataset$Number ^ dataset$Power
ggplot(dataset, aes(x = Number, y = Result, colour = factor(Power))) +
geom_line()

HTH,

Thierry


------------------------------------------------------------------------
----
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek
team Biometrie & Kwaliteitszorg
Gaverstraat 4
9500 Geraardsbergen
Belgium

Research Institute for Nature and Forest
team Biometrics & Quality Assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium

tel. + 32 54/436 185
Thierry.Onkelinx op inbo.be
www.inbo.be

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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 op r-project.org 
> [mailto:r-help-bounces op r-project.org] Namens Eduardo de Oliveira Horta
> Verzonden: woensdag 5 januari 2011 3:56
> Aan: r-help
> Onderwerp: [R] Adding lines in ggplot2
> 
> Hello,
> 
> this is probably a recurrent question, but I couldn't find 
> any answers that didn't involve the expression "data 
> frame"... so perhaps I'm looking for something new here.
> 
> I wanted to find a code equivalent to
> 
> > x=sqrt(1:10)
> > y=log(1:10)
> > plot(1:10, x, type="lines", col="darkgreen") lines(1:10, y, 
> col="red")
> 
> to use with ggplot2. I've tried
> 
> > x=sqrt(1:10)
> > y=log(1:10)
> > qplot(1:10, x, geom="line", colour=I("darkgreen")) 
> geom_line(1:10, y, 
> > colour="red")
> Error: ggplot2 doesn't know how to deal with data of class numeric
> 
> but it seems that the "data frame restriction" is really very 
> restrictive here. Any solutions that don't imply using 
> as.data.frame to my data?
> 
> Thanks in advance, and best regards!
> 
> Eduardo Horta
> 
> 	[[alternative HTML version deleted]]
> 
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