>>>>> Ramnik Bansal <ramnik.ban...@gmail.com>
>>>>> on Sat, 20 May 2017 08:52:55 +0530 writes:
> Taking this question further.
> If I use a complex number or a numeric as an operand in logical
> operations, to me it APPEARS that these two types are first coerced to
> LOGICAL internally and then THIS logical output is further used as the
> operand.
> For eg.
>> x <- 4+5i; c(x & F, x & T, x | F, x | T)
> [1] FALSE TRUE TRUE TRUE
> This output is consistent with
>> x <- 4+5i; c(as.logical(x) & F, as.logical(x) & T, as.logical(x) | F,
as.logical(x) | T)
> [1] FALSE TRUE TRUE TRUE
> This consistency makes me draw an on-the-surface conclusion that in
> the case of logical operations if the operand is not of type 'logical'
> it is first coerced into 'logical'.
That conclusion is wrong as you show below.
Rather, as the error message says,
logical
"operations are possible only for numeric, logical or complex types"
Again:
1) Logical/Arithmetic operations "work" with "numeric-like" types, namely
numeric, logical or complex, (and numeric = {integer, double})
==> all other types give an error (the one you've cited twice)
2) For "numeric-like" types and *logical* operations (&, |, !; plus && and ||)
the equivalent of as.logical() is applied before performing the Op.
Seems pretty consistent ...
and also according to the principle of "least surprise" (for me at least).
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