[R] Fw: length() misbehaving?: More

David Parkhurst parkhurs at indiana.edu
Fri Mar 14 16:44:14 CET 2003

With the problem below, I've discoved that
does give me the correct count for the number of "tr" entries.  (The same behavior
occurs for the "c" level of the cnd95 factor.)  It appears that
is finding both "tr" AND NA entries.  Is this a bug, or is it to be expected?


Subject: length() misbehaving?

> 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

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