Hello! Please, anybody help me. Can I calculate area of density was created by:> D <- density(x)In other words I want to know area under curve 'plot(D)' and It's good to calculate area before and after 0 separately. -- View this message in context: http://www.nabble.com/Area-of-density-tp19338958p19338958.html Sent from the R help mailing list archive at Nabble.com.
On 05/09/2008 4:32 PM, pragmatic wrote:> Hello! > Please, anybody help me. > > Can I calculate area of density was created by: >> D <- density(x) > In other words I want to know area under curve 'plot(D)'That should be 1.> and It's good to calculate area before and after 0 separately.That's harder, but a good approximation should be sum(x < 0)/length(x) and sum(x > 0)/length(x). Duncan Murdoch
On 6/09/2008, at 8:32 AM, pragmatic wrote:> > Hello! > Please, anybody help me. > > Can I calculate area of density was created by: >> D <- density(x) > In other words I want to know area under curve 'plot(D)' > and It's good to calculate area before and after 0 separately.(1) You could use splinefun() foo <- splinefun(D$x,D$y) integrate(foo,min(D$x),0) integrate(foo,0,max(D$x)) or you could use simp() from http://finzi.psych.upenn.edu/R/Rhelp02a/archive/134918.html with(D,simp(y=y[x<0],x=x[x<0])) with(D,simp(y=y[x>0],x=x[x>0])) You'll get different answers, neither of which is ``correct''. cheers, Rolf Turner ###################################################################### Attention:\ This e-mail message is privileged and confid...{{dropped:9}}