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Hervé Pagès

2015-Apr-14 05:19 UTC

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

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:

   ?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.

Thanks,
H.

-- 
Herv? Pag?s

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpages at fredhutch.org
Phone:  (206) 667-5791
Fax:    (206) 667-1319

Avraham Adler

2015-Apr-14 06:24 UTC

head link

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

On Tue, Apr 14, 2015 at 1:19 AM, Herv? Pag?s <hpages at fredhutch.org>
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:

Hello, Herv?

Per help("as.integer"): "Note that current implementations of R
use
32-bit integers for integer vectors, so the range of representable
integers is restricted to about +/-2*10^9: doubles can hold much
larger integers."

5000000000 ~ 2^32.2 > 2^32 > 2*10^9

Avi

>
>   ?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.
>
> Thanks,
> H.
>
> --
> Herv? Pag?s
>
> Program in Computational Biology
> Division of Public Health Sciences
> Fred Hutchinson Cancer Research Center
> 1100 Fairview Ave. N, M1-B514
> P.O. Box 19024
> Seattle, WA 98109-1024
>
> E-mail: hpages at fredhutch.org
> Phone:  (206) 667-5791
> Fax:    (206) 667-1319
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

Martin Maechler

2015-Apr-14 06:32 UTC

head link

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

> 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.

Martin

> -- 
> Herv? Pag?s
> ...................

Hervé Pagès

2015-Apr-14 06:36 UTC

head link

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

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
>
>
>> --
>> Herv? Pag?s
>> ...................
-- 
Herv? Pag?s

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpages at fredhutch.org
Phone:  (206) 667-5791
Fax:    (206) 667-1319

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