I'm having a weird problem with length(), in R1.6.1 under windows2000. I have a
dataframe called byyr, with ten columns, the first of which is named cnd95.
summary(byyr) shows that byyr$cnd95 contains the factor level "tr" 66 times. Also,
when I enter byyr$cnd95 at the command line, I can count 66 "tr" elements in the
resulting vector. However, when I enter
n95trt <- length(byyr$cnd95[byyr$cnd95=="tr"])
n95trt
the result is 68! Any ideas why this is happening, and how I can fix the miscount?
(That column also contains 69 entries of "c", and (relevantly?) two NA's.)
Thanks for any help.
Dave Parkhurst