problem with "which"
Melanie Abecassis <Melanie.Abecassis at noaa.gov> wrote in news:481002B0.3080704 at noaa.gov:
Hi, I'm having trouble with the "which" or the "seq" function, I'm not sure. Here's an example :
lat=seq(1,2,by=0.1) lat
[1] 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0
which(lat==1)
[1] 1
which(lat==1.1)
snip
[1] 7
which(lat==1.7)
*integer(0)* This doesn't seem to happen with integers. Am I missing something ?? Is there a better function for non-integers ?
Read the FAQ (Section 7.31 Why doesn't R think these numbers are equal? http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-these-numbers-are-equal_003f and look at this:
lat - 1.7
[1] -7.000000e-01 -6.000000e-01 -5.000000e-01 -4.000000e-01 [5] -3.000000e-01 -2.000000e-01 -1.000000e-01 2.220446e-16 [9] 1.000000e-01 2.000000e-01 3.000000e-01
David Winsemius