Removing outliers in R plot function

Question

I'm trying to do a scatterplot in R and would love to remove an outlier I've already identified.

My plot function:

attach(L)
plot(independent variable, dependent variable, main="TITLE", xlab="x-axis label", ylab="y-axis label", pch=18, col="blue")
text(independent variable, dependent variable, data label, cex=0.6, pos=4, col="red")

My best-fit line:

abline(lm(dependent variable ~ independent variable))

Is there a simple way I can remove "ISR" on the graph below without installing any additional packages? Thanks!

Answer 1

1) If you just want to exclude $y$ values above (or below) some specific value, use the ylim argument to plot. e.g. ,ylim=c(0,20) should work for the above plot.

2) You say you've already "identified" the outliers. If you have a logical variable or expression that indicates the outliers, you can use that in your plot.

e.g. consider:

 # let's make a small data example
 x=1:10
 y=rnorm(10)
 y[5]=30
 par(mfrow=c(1,2))

 plot(x,y)  # outlier problem
 yout=y>5   # some logical rule for identifying an outlier
 plot(x[!yout],y[!yout])  # toss them out