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Wierd problem comparing numeric values and list using == (PR#1073)

3 messages · Warnes, Gregory R, Peter Dalgaard, John Chambers

Warnes, Gregory R
# 
Under R 1.3.0 on Solaris and Windows NT  there seems to be a bug in == when
applied to elements of a list, particularly when one of the elements is of
mode integer:

	> list(1) == list(1)
	[1] FALSE
	> 1 == list(1)
	[1] TRUE
	> as.integer(1)==list(as.integer(1))
	[1] FALSE
	> as.integer(1)==list(as.double(1))
	[1] FALSE
	> list(as.integer(1))==list(as.integer(1))
	[1] FALSE
	> list(as.integer(1))==as.integer(1)
	[1] FALSE
	> list(as.double(1))==list(as.double(1))
	[1] FALSE

However, these cases work:

	> as.double(1)==list(as.integer(1))
	[1] TRUE
	> list(as.integer(1))==as.double(1)
	[1] TRUE

Replacing the bare integer/double with a vector constructed with c() doesn't
change the results, and comparing between vectors created with c() appears
correct.

-Greg

--please do not edit the information below--

Version:
 platform = i386-pc-mingw32
 arch = x86
 os = Win32
 system = x86, Win32
 status = 
 major = 1
 minor = 3.0
 year = 2001
 month = 06
 day = 22
 language = R

Windows NT 4.0 (build 1381) Service Pack 5

Search Path:
 .GlobalEnv, package:ctest, Autoloads, package:base


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Peter Dalgaard
# 
gregory_r_warnes@groton.pfizer.com writes:
It is not entirely clear what we *should* be doing here. S (-PLUS 3.4)
is at least consistent:
Error in list(1) == list(1): == operation on mode "list" undefined
Dumped
Error in 1 == list(1): == operation on mode "list" undefined
Dumped
Error in as.integer(1) == list(as.integer(1)): == operation on mode "list"
        undefined
Dumped
...

so one might argue that you shouldn't do that in the first place...
(or that the bug is that we do not expressly forbid doing this.)

        -p
1 day later
John Chambers
#
Peter Dalgaard BSA wrote:
As of 1.4, we will have the `identical' function, which is the right way
to do such comparisons in any case.

So I'd vote for making a use of the comparison operators an error unless
the type is correct (or there is a method defined).  There is even code
in relop.c (commented out) that looks like the right test.  Any
objections?

John