[R] Fitting a Triangular Distribution to Bivariate Data
Jinsong Zhao
jszhao at yeah.net
Thu Dec 23 14:50:14 CET 2010
On 2010-12-23 2:19, David Bapst wrote:
> Hello,
> I have some xy data which clearly shows a non-monotonic, peaked
> triangular trend. You can get an idea of what it looks like with:
>
> x<-1:20
> y<-c(2*x[1:10]+1,-2*x[11:20]+42)
>
> I've tried fitting a quadratic, but it just doesn't the data-structure
> with the break point adequately. Is there anyway to fit a triangular
> or 'tent' function to my data in R?
>
> Some sample code would be appreciated; I'm not new to R, but I
> sometimes have difficulty understanding the model-fitting functions
> (finally figured out how to extrapolate with predict() today!)
>
> Thanks!
> -Dave Bapst, UChicago
>
Hi,
you may try the following code:
> library(triangle)
> library(fitdistrplus)
> summary(fitdist(y, "triangle", start = list(a = 1.9, b= 21.1, c = 11.5)))
Fitting of the distribution ' triangle ' by maximum likelihood
Parameters :
estimate Std. Error
a -1.400007 2.3523724
b 23.627448 1.9804026
c 13.000000 0.1107073
Loglikelihood: -62.41994 AIC: 130.8399 BIC: 133.8271
Correlation matrix:
a b c
a 1.00000000 -0.14537297 -0.01203898
b -0.14537297 1.00000000 -0.01439500
c -0.01203898 -0.01439500 1.00000000
HTH ...
Jinsong Zhao
More information about the R-help
mailing list