[R] Trying to replicate error message in subset()

[Michael Rennie]

Hi, there

I am trying to replicate an error message in subset() to see what it is 
that I'm doing wrong with the datasets I am trying to work with.

Essentially, I am trying to pass a string vector to subset() in order to 
select a specific collection of cases (i.e., I have data for these cases in 
one table, and want to select data from another table that match up with 
the cases in the first table).

The error I get is as follows:

Warning messages:
1: longer object length
         is not a multiple of shorter object length in: is.na(e1) | is.na(e2)
2: longer object length
         is not a multiple of shorter object length in: `==.default`(LAKE, g)

Here is an example case I've been working with (which works) that I've been 
trying to "break"such that I can get this error message to figure out what 
I am doing wrong in my case.

y1<-rnorm(100, 2)
x1<-rep(1:5, each=20)
x2<-rep(1:2, each=10, times=10)

ex.dat<-data.frame(cbind(y1,x1,x2))


ex.dat$x1<-factor(ex.dat$x1, labels=c("A", "B", "C", "D", "E"))
ex.dat$x2<-factor(ex.dat$x2, labels=c("B", "D"))

a<-c("D", "F")
a

new.dat<-subset(ex.dat, x1 == a)
new.dat

I thought maybe I was getting errors because I had cases in my selection 
vector ('a' in this case) that weren't in my ex.dat list, but subset 
handles this fine and just gives me what it can find in the larger list.

Any thoughts on how I can replicate the error? As far as I can tell, the 
only difference between the case where I am getting errors and the example 
above is that the levels of x1 in my case are words (i.e., "Smelly", 
"Howdy"), but strings are strings, aren't they?

Mike


Michael Rennie
Ph.D. Candidate, University of Toronto at Mississauga
3359 Mississauga Rd. N.
Mississauga, ON  L5L 1C6
Ph: 905-828-5452  Fax: 905-828-3792
www.utm.utoronto.ca/~w3rennie