For a given random variable rv, for instance, rv = rnorm(1000), I plot its density curve and calculate some quantiles: plot(density(rv)) P10P50P90 = = quantile(rv,probs = c(10,50,90)/100) I would like to color the area between P10 and P90 and under the curve and mark the P50 on the curve.> rv = rnorm(1000) > plot(density(rv)) > P10P50P90 = = quantile(rv,probs = c(10,50,90)/100)Could you please teach me how to do these using R? Thanks, -james
<guox <at> ucalgary.ca> writes:> > For a given random variable rv, for instance, rv = rnorm(1000), > I plot its density curve and calculate some quantiles: > plot(density(rv)) > P10P50P90 = = quantile(rv,probs = c(10,50,90)/100) > I would like to color the area between P10 and P90 and under the curve > and mark the P50 on the curve. > > > rv = rnorm(1000) > > plot(density(rv)) > > P10P50P90 = = quantile(rv,probs = c(10,50,90)/100) > > Could you please teach me how to do these using R? > Thanks, > -james >see ?polygon Here after is an example of the use of polygon to solve your problem: rv <- rnorm(1000) drv <- density(rv) plot(drv) # further steps: # 1. compute quantiles # 2. determine the x and y of the area that must be drawn # 3. drawn # 4. add q.5 info qrv <- quantile(rv, prob=c(0.1, 0.9)) select <- qrv[1] <= drv$x & drv$x <= qrv[2] polygon(x = c(qrv[1], drv$x[select], qrv[2]), y = c(0, drv$y[select], 0, col='blue') abline(v= quantile(rv, p=0.5), lty=2) Hope this will help. Matthieu
I did similar things with polygon(). Le mar. 10 mars ? 13:30, guox at ucalgary.ca a ?crit :> For a given random variable rv, for instance, rv = rnorm(1000), > I plot its density curve and calculate some quantiles: > plot(density(rv)) > P10P50P90 = = quantile(rv,probs = c(10,50,90)/100) > I would like to color the area between P10 and P90 and under the curve > and mark the P50 on the curve. > >> rv = rnorm(1000) >> plot(density(rv)) >> P10P50P90 = = quantile(rv,probs = c(10,50,90)/100) > > Could you please teach me how to do these using R? > Thanks, > -james > > ______________________________________________ > 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.