On Wed, 2004-07-07 at 18:29, Bret Collier wrote: > R-users, > I have been using R for about 1 year, and I have run across a > couple of graphics problem that I am not quite sure how to address. I have > read up on the email threads regarding the differences between density and > relative frequencies (count/sum(count) on the R list, and I am hoping that > someone could provide me with some advice/comments concerning my > approach. I will admit that some of the underlying mathematics of the > density discussion are beyond my current understanding, but I am looking > into it. > > I have a data set (600,000 obs) used to parameterize a probabilistic causal > model where each obs is a population response for one of 2 classes (either > regs1 and regs2). I have been attempting to create 1 marginal probability > plot with 2 lines (one for each class). Using my rather rough code, I > created a plot that seems to adhere to the commonly used (although from > what I can understand wrong) relative frequency histogram approach. > > My rough code looks like this: > > bk <- c(0, .05, .1, .15, .2, .25,.3, .35, 1) > par(mfrow=c(1, 1)) > fawn1 <- hist(MFAWNRESID[regs1], plot=F, breaks=bk) > fawn2 <- hist(MFAWNRESID[regs2], plot=F, breaks=bk) > count1 <- fawn1$counts/sum(fawn1$counts) > count2 <- fawn2$counts/sum(fawn2$counts) > b <- c(0, .05, .1, .15, .2, .25, .3, .35) > plot(count1~b,xaxt="n", xlim=c(0, .5), ylim=c(0, .40), pch=".", bty="l") > lines(spline(count1~b), lty=c(1), lwd=c(2), col="black") > lines(spline(count2~b), lty=c(2), lwd=c(2), col="black") > axis(side=1, at=c(0, .05, .1, .15, .2, .25, .3, .35))
Have you considered density() and plot.density() by any change ? > Using the above, I get frequency values for regs1 that look like this > (which is the same as output for my probabilistic model): > > count1 > [1] 1.213378e-01 3.454324e-01 3.365343e-01 1.580839e-01 3.342101e-02 > [6] 4.698426e-03 4.488942e-04 4.322685e-05 I would tend to use the term proportion rather than frequency. > First, count1 is the frequency of occurrence within range 0-0.05, but when > plotted is the value at b=0 and does not really represent the range? Are > there any suggestions on a technique to approach this? You can plot it in the mid-points like hist() does. fawn1$mids would give you these values. > Next: Using the above code, the x-axis values end at 0.35, but the axis > continues (because bk ends at 1)? While there is the chance of occurrence > out past .35, it is low and I want to extend the lines to about .35 and > clip the x-axis. But, I have been unable to figure out how to clip Could > someone point me in the correct direction? In your plot() function, set xlim=c(0,0.35). If you mean 'clipping' as in truncating the density, then you probably need to do re-adjust your proportions such that they sum up to 1. ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
