Dear list,
I'm afraid this is a mundane question. Here's the background: I've
produced a function which allows me to sequentially measure angles and
distances from a specified reference point to a curve defined by
empirical data points while (i.e. using a while loop) the angle being
measured is within certain bounds. Because the curve is circular I
need to pars the data into basically an "upper" curve and "lower"
curve. I tried to do this with an if statement, specifically:
ycrit<-subset(data,subset=data$x==min(data$x)
y.max<-length*sin(angle)+y.ref #length, angle and y.ref are given
if(y.max<ycrit){
........
}
Now the problem: The while loop works for 4 iterations, until I get
the error message:
"Error in if (y.max < ycrit) { : missing value where TRUE/FALSE needed"
When I forced the function to print y.max and ycrit for each iteration
of the while loop, it returns finite real numbers, including ycrit =
153.5 and y.max = 245.16 for the step which returns the error message.
Any ideas about what's going on here--why does R "think" that
245.16<153.5 is "missing," or is anything other than TRUE/FALSE? Am I
using "if" incorrectly? In which case would it be more appropriate to
perhaps create subsets of the data points based on < or > ycrit?
Thanks in advance for any guidance--
Andy
--
Andrew J. Rominger
Department of Biological Sciences
Stanford University
[EMAIL PROTECTED]
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