[Rd] possible bug: NULL equality in lists.
Charles Dupont
charles.dupont at vanderbilt.edu
Tue Mar 7 15:39:26 CET 2006
I was messing around with R and I found an example R behaving oddly:
a <- alist(NULL, "bob", c(3,6,2,3))
a
a == 'NULL'
a == "NULL"
a == 'cat'
If I create a list with a NULL value
>a <- alist(NULL, "bob", c(3,6,2,3))
>a
[[1]]
NULL
[[2]]
[1] "bob"
[[3]]
c(3, 6, 2, 3)
and run some tests on 'a', the '== "NULL' test returns TRUE for the NULL
entry in the list 'a'.
>a == 'NULL'
[1] TRUE FALSE FALSE
>a == "NULL"
[1] TRUE FALSE FALSE
>a == 'cat'
[1] FALSE FALSE FALSE
This is consistent for every example of NULL's in a list that I can
think of.
Is this a bug or undocumented correct behavior?
Here is my version output
platform i486-pc-linux-gnu
arch i486
os linux-gnu
system i486, linux-gnu
status
major 2
minor 2.0
year 2005
month 10
day 06
svn rev 35749
language R
Thanks
Charles
--
Charles Dupont Computer System Analyst School of Medicine
Department of Biostatistics Vanderbilt University
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