[Rd] behavior of as.integer("5000000000")

[Hervé Pagès]

On 04/13/2015 11:32 PM, Martin Maechler wrote:
>
>> Hi,
>>     > as.integer("5000000000")
>>     [1] 2147483647
>>     Warning message:
>>     inaccurate integer conversion in coercion
>
>>     > as.integer("-5000000000")
>>     [1] NA
>>     Warning message:
>>     inaccurate integer conversion in coercion
>
>> Is this a bug or a feature? The man page suggests it's the
>> latter:
>
> I think you mean the "former", a bug.
>
> and I agree entirely, see the following  " 2 x 2 " comparison :
>
>    > N <- 5000000000000 * 8^-(0:7)
>    > as.integer(N)
>    [1]         NA         NA         NA         NA 1220703125  152587890   19073486    2384185
>    Warning message:
>    NAs introduced by coercion
>    > as.integer(-N)
>    [1]          NA          NA          NA          NA -1220703125  -152587890   -19073486
>    [8]    -2384185
>    Warning message:
>    NAs introduced by coercion
>    > as.integer(as.character(N))
>    [1] 2147483647 2147483647 2147483647 2147483647 1220703125  152587890   19073486    2384185
>    Warning message:
>    inaccurate integer conversion in coercion
>    > as.integer(as.character(-N))
>    [1]          NA          NA          NA          NA -1220703125  -152587890   -19073486
>    [8]    -2384185
>    Warning message:
>    inaccurate integer conversion in coercion
>
>
>
>>     ‘as.integer’ attempts to coerce its argument to be of integer
>>     type.  The answer will be ‘NA’ unless the coercion succeeds.
>
>> even though someone could always argue that coercion of "5000000000"
>> succeeded (for some definition of "succeed").
>
>> Also is there any reason why the warning message is different than
>> with:
>
>>     > as.integer(-5000000000)
>>     [1] NA
>>     Warning message:
>>     NAs introduced by coercion
>
>> In the case of as.integer("-5000000000"), it's not really that the
>> conversion was "inaccurate", it's a little bit worse than that. And
>> knowing that NAs where introduced by coercion is important.
>
> Yes.
> The message is less a problem than the bug, but I agree we
> should try to improve it.

Sounds good. Thanks Martin,

H.

>
> Martin
>
>
>> --
>> Hervé Pagès
>> ...................

-- 
Hervé Pagès

Program in Computational Biology
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