[R] a < b < c is alway TRUE
murdoch at stats.uwo.ca
Fri Jul 6 15:35:14 CEST 2001
On Fri, 6 Jul 2001 13:21:51 +0200, you wrote in message
<3B45BB6F.6582.E1B7B at localhost>:
>what's surprising is the following:
>because of symmetry i'd expect TRUE>1 to be TRUE.
In R like C, FALSE is 0 and TRUE is 1. This is a bad thing, but it's
too late to change it now. With that substitution, all the results
look reasonable: 0>1, 1<1 and 1>1 are all false, but 0<1 is true.
Why a bad thing? Because it leads to absurdities like this whole
thread has been discussing!
What should they have done? They should have done what Fortran,
Pascal, etc. do, and have a separate logical or boolean type that
isn't automatically converted to a numerical type. In Pascal for
instance, "3 < 2 < 1" is flagged as a syntax error, because you can't
compare a boolean to an integer. If you really want to do the weird
comparison that R is doing, you need to enter it as "ord(3 < 2) < 1",
and any reader will see that you're doing something weird.
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