From: Bret Collier <bacolli_at_uark.edu>

Date: Thu 08 Jul 2004 - 03:29:40 EST

R-help@stat.math.ethz.ch 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 Received on Thu Jul 08 03:32:13 2004

Date: Thu 08 Jul 2004 - 03:29:40 EST

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))

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

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?

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?

**TIA,
**
Bret A. Collier

Arkansas Cooperative Fish and Wildlife Research Unit
Department of Biological Sciences University of Arkansas

R-help@stat.math.ethz.ch 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 Received on Thu Jul 08 03:32:13 2004

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