[R] merging data frames gives all NAs

[Erik Iverson]

James Rome wrote:
> On 2/1/2010 5:51 PM, David Winsemius wrote:
> I figured this out finally. I really believe that the R help write-ups
> are sorely lacking. 

The help docs are probably not the best way to learn R, but they are 
great for users of the functions.  I have found that after going through 
an introduction book on R or online tutorial (plus experience), that the 
help system in R is really, really good at *documenting the behavior of 
the functions*, which is the point of them.

As another general hint from someone who has learned R slowly over time, 
when something happens that you don't understand on "real" data, 
construct a minimal example data.frame and try out your code on that. 
Also, learning how to use browser() or the debug package has been very 
useful.