donahc...@me.com wrote:
On Dec 30, 2009, at 10:10 PM, Jim Lemon wrote:
On 12/31/2009 02:41 PM, donahc...@me.com wrote:
Hi,
I'm pretty much an R noob and I'm missing some paradigm in R I
think. I can't figure our how to compare numerics. here's a
transcript of my tests. Any pointers?
Hi donahchoo,
You're comparing the printed value of range_sd, which has been
truncated, to the actual value. As the printout says, the difference
is small, but present. If you set range_sd to the printed value:
range_sd<-34.40783
the comparisons will return TRUE.
Jim
Thanks, Jim. I figured this out after sending the email, but I still
can't compare. Here's some more tests, note that all.equal returns true
but so does !=
actual_mean <- mean( range)
actual_sd <- sd( range)
expected_mean <- 218.213483146067
expected_sd <- 159.277118043936
print(paste("expected_mean", expected_mean))
print(paste("actual_mean", actual_mean))
print(paste("expected_sd", expected_sd))
print(paste("actual_sd", actual_sd))
if( expected_mean != actual_mean ) {
stop( "not equal" )
}
Output:
> source("/Users/adhamh/Developer/r/test.r")
[1] "expected_mean 218.213483146067"
[1] "actual_mean 218.213483146067"
[1] "expected_sd 159.277118043936"
[1] "actual_sd 159.277118043936"
Error in eval.with.vis(expr, envir, enclos) : not equal
> identical(expected_mean, actual_mean)
[1] FALSE
> all.equal(expected_mean, actual_mean)
[1] TRUE
>
Your code is not reproducible, but it seems fairly clear
that you haven't yet read the help pages for identical()
and all.equal(); or, if you have, you haven't done so
very carefully. For ?identical, you'll find this:
"The function all.equal is also sometimes used to test
equality this way, but was intended for something
different: it allows for small differences in numeric
results."
For ?all.equal, you'll see mention of an argument 'tolerance'.
As a new R-user, you would be well advised to get very
familiar with the '?' key.
Welcome to R.
-Peter Ehlers
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--
Peter Ehlers
University of Calgary
403.202.3921
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
