[R] How to plot a shifted Gamma distribution

[(Ted Harding)]

On 13-Feb-2014 15:30:43 Rodrigo Cesar Silva wrote:
> I have the parameters of a gamma distribution that I am trying to plot.
> The parameters are shape = 2, scale = 5.390275 and the minimum value
> x0 is 65.44945.
> 
> Since the gamma is shifted by x0, we have
> 
                Mean = shape*scale + x0 = 76.23
> 
> My question is, how can I do it in r?
> 
> I was trying to use dgamma function, but I saw no options to offset
> the gamma distribution. I can only use the shape and scale parameters,
> like this:
> 
>> x <- seq(from=0, to=100, length.out=100)
> 
>> plot(x, dgamma(x, shape=2, scale=5.390275),
>       main="Gamma",type='l')

If all that is happening is that the distribution is the same as that
of a Gamma distribution with origin at 0, but simply shifted to the
right by an amount x0 (though I am wondering what context this could
arise in), then the commands

  x <- seq(from=0, to=100, length.out=100)
  x0 <- 65.44945
  plot(x+x0, dgamma(x, shape=2, scale=5.390275),
       main="Gamma",type='l')

will produce such a plot. However, I wonder if you have correctly
expressed the problem!

Ted.

> This generates a distribution with origin equal zero, but I want the
> origin to be x0
> 
> How can I handle shifted gamma distribution in r?
> 
> Thanks a lot!
> Rodrigo.

-------------------------------------------------
E-Mail: (Ted Harding) <Ted.Harding at wlandres.net>
Date: 13-Feb-2014  Time: 17:27:29
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