R help - Jul 2008 - Plot Mixtures of Synthetically Generated Gamma Distributions

Hi,

I have the following vector
which is created from 3 distinct distribution (three components) of gamma:

x=c(rgamma(30,shape=.2,scale=14),rgamma(30,shape=12,scale=10),rgamma(30,shape=5,scale=6))

I want to plot the density curve of X, in a way that it shows
a distinct 3 curves that represent each component.

How can I do that?

I tried this but doesn't work:

lines(density(x))

Please advise.

- Gundala Viswanath
Jakarta - Indonesia

Dear Gundala,

It's just a starting points. I'm sure it could be better. Try this:

set.seed(123)
x=c(rgamma(30,shape=.2,scale=14),rgamma(30,shape=12,scale=10),rgamma(30,shape=5,scale=6))

plot(density(x[1:30]),col=2,xlim=range(0,max(density(x)$x)),type='l',main="Density
for your vector")
points(density(x[31:60]),col=1,type='l')
points(density(x[61:90]),col=4,type='l')
legend("topright",paste('Type',1:3,sep=""),col=c(2,1,4),lty=1)

HTH,

Jorge




On Sun, Jul 6, 2008 at 11:24 PM, Gundala Viswanath <gundalav@gmail.com>
wrote:
> Hi,
>
> I have the following vector
> which is created from 3 distinct distribution (three components) of gamma:
>
>
>
x=c(rgamma(30,shape=.2,scale=14),rgamma(30,shape=12,scale=10),rgamma(30,shape=5,scale=6))
>
> I want to plot the density curve of X, in a way that it shows
> a distinct 3 curves that represent each component.
>
> How can I do that?
>
> I tried this but doesn't work:
>
> lines(density(x))
>
> Please advise.
>
> - Gundala Viswanath
> Jakarta - Indonesia
>
> ______________________________________________
> R-help@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.
>
	[[alternative HTML version deleted]]

Dear Gundala,

It's just a starting points and I'm sure completely sure it will be
improved. Try this (for now):

set.seed(123)
x=c(
rgamma(30,shape=.2,scale=14),
rgamma(30,shape=12,scale=10),
rgamma(30,shape=5,scale=6))

plot(density(x[1:30]),col=2,xlim=range(0,max(density(x)$x)),type='l',main="Density
for your vector")
points(density(x[31:60]),col=1,type='l')
points(density(x[61:90]),col=4,type='l')
legend("topright",paste('Type',1:3,sep=""),col=c(2,1,4),lty=1)


Also, see ?density, ?points and ?plot for more information.

HTH,

Jorge

On Sun, Jul 6, 2008 at 11:24 PM, Gundala Viswanath <gundalav@gmail.com>
wrote:
> Hi,
>
> I have the following vector
> which is created from 3 distinct distribution (three components) of gamma:
>
>
>
x=c(rgamma(30,shape=.2,scale=14),rgamma(30,shape=12,scale=10),rgamma(30,shape=5,scale=6))
>
> I want to plot the density curve of X, in a way that it shows
> a distinct 3 curves that represent each component.
>
> How can I do that?
>
> I tried this but doesn't work:
>
> lines(density(x))
>
> Please advise.
>
> - Gundala Viswanath
> Jakarta - Indonesia
>
> ______________________________________________
> R-help@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.
>
	[[alternative HTML version deleted]]

I know very little about graphics, so my primitive and brute force solution
would be

plot(density(x[1:30]),col="blue");lines(density(x[31:60]),col="red");lines(density(x[61:90]),col="green")


--- On Mon, 7/7/08, Gundala Viswanath <gundalav at gmail.com> wrote:
> From: Gundala Viswanath <gundalav at gmail.com>
> Subject: [R] Plot Mixtures of Synthetically Generated Gamma Distributions
> To: r-help at stat.math.ethz.ch
> Received: Monday, 7 July, 2008, 1:24 PM
> Hi,
> 
> I have the following vector
> which is created from 3 distinct distribution (three
> components) of gamma:
> 
>
x=c(rgamma(30,shape=.2,scale=14),rgamma(30,shape=12,scale=10),rgamma(30,shape=5,scale=6))
> 
> I want to plot the density curve of X, in a way that it
> shows
> a distinct 3 curves that represent each component.
> 
> How can I do that?
> 
> I tried this but doesn't work:
> 
> lines(density(x))
> 
> Please advise.
> 
> - Gundala Viswanath
> Jakarta - Indonesia
> 
> ______________________________________________
> 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.

Are you trying to look at the difference in the gamma distributions due to
variations in the shape and scale parameters? In this case, the following
approach might be more straightforward:


## assign parameter values
params <- list(curve1=c(1,1),curve2=c(1,2),curve3=c(1,3))

## define function
gammafun <- function(shape,scale) {
  p <- seq(0.001,0.999,length=1000)
  x <- qgamma(p,shape,scale)
  y <- dgamma(x,shape,scale)
  list(x=x,y=y)
}

## apply function to parameters
dat <- lapply(params,function(p) gammafun(p[1],p[2]))

## plot lines
xlim <- range(sapply(dat,`[[`,"x"))
ylim <- range(sapply(dat,`[[`,"y"))
plot.new()
plot.window(xlim,ylim)
for( i in 1:3 ) lines(dat[[i]],col=i)
lapply(1:2,axis)
box()
legend("topright",lty=1,col=1:3,legend=names(dat))





----- Original Message ----
From: Gundala Viswanath <gundalav at gmail.com>
To: r-help at stat.math.ethz.ch
Sent: Sunday, July 6, 2008 8:24:06 PM
Subject: [R] Plot Mixtures of Synthetically Generated Gamma Distributions

Hi,

I have the following vector
which is created from 3 distinct distribution (three components) of gamma:

x=c(rgamma(30,shape=.2,scale=14),rgamma(30,shape=12,scale=10),rgamma(30,shape=5,scale=6))

I want to plot the density curve of X, in a way that it shows
a distinct 3 curves that represent each component.

How can I do that?

I tried this but doesn't work:

lines(density(x))

Please advise.

- Gundala Viswanath
Jakarta - Indonesia

______________________________________________
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.