[R] Plot of function seems to cut off near edge of domain
Hello helpful R folks,
I am simply trying to graph a quarter circle centered at the origin in the
first quadrant. When I set the xlim of the plot to the radius of the
circle, the plot appears correct. However, I'd like to see a slight
extension of the axes beyond the domain of the function itself. When I do
this, a portion of the plot seems to be missing by the edge of the domain.
Here is the code for both of the plots:
dev.off()
plot.new()
#Set up two-figure plot
par(mfrow=c(1,2),pty='s')
g-function(x){sqrt(2500-x^2)}
#Figure 1, with xlim at the radius of the circle
plot(g,axes=F,xlim=c(0,50),ylim=c(0,50))
axis(1,pos=0)
axis(2,pos=0)
#Figure 2, with xlim beyond the radius of the circle
plot(g,axes=F,xlim=c(0,60),ylim=c(0,60))
axis(1,pos=0)
axis(2,pos=0)
Notice that the second graph doesn't appear to intersect the x-axis, while
the first one does. Any ideas why that might be the case? Here's an image
of what I see in case that's useful:
http://r.789695.n4.nabble.com/file/n4507954/Cut_off_Quarter_Circle.png
Thanks in advance for the help!
-Chad Mills
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[R] Simple question regarding domain restrictions/piecewise functions in R
I am a novice R user.
I would like to be able to graph some simple piecewise functions/functions
with domain restrictions in R, but I'm having trouble defining such
functions. For example, I would like to define the following function:
f(x)={x^2 if -1xx; 1 if 2x3}
Notably, the function is undefined outside of domain (-1,1)U(2,3). My best
attempt in R is something like this:
f-function(x) ifelse(-1x x1,x^2,ifelse(2=x x=3,1,as.null()))
This approach works fine for values within the domain. But, naturally, when
I try values outside of the domain I get an error. Consequently, when I try
to graph such a function:
plot(f)
I get the following error:
Error in ifelse(2 = x x = 3, 1, as.null()) :
replacement has length zero
I realize that I could create vectors of x-y points and plot using the
plot(x,y) command, but it seems to me that I should be able to define a
piecewise function symbolically and just graph it. Am I wrong? Any help
would be greatly appreciated.
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Re: [R] Simple question regarding domain restrictions/piecewise functions in R
Yes! Thanks. It was just the NA value instead of the as.null that does
the trick. Correct code for the original piecewise I stated (for those who
might be looking later) is:
f - function(x){
ifelse((-1 x x 1),x^2,ifelse((2xx3),1,NA))
}
plot(f,xlim=c(-1,3))
-Chad Mills
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