[Rd] Inconsistency in handling of numeric input with %d by sprintf

[Michael Chirico]

https://github.com/Rdatatable/data.table/issues/2171

The fix was easy, it's just surprising to see the behavior change almost on
a whim. Just wanted to point it out in case this is unknown behavior, but
Evan seems to have found this as well.

On Tue, May 23, 2017 at 12:00 PM, Michael Chirico <michaelchirico4 at gmail.com
> wrote:

> Astute observation. And of course we should be passing integer when we use
> %d. It's an edge case in how we printed ITime objects in data.table:
>
>
> On Tue, May 23, 2017 at 11:53 AM, Joris Meys <jorismeys at gmail.com> wrote:
>
>> I initially thought this is "documented behaviour". ?sprintf says:
>>
>> Numeric variables with __exactly integer__ values will be coerced to
>> integer. (emphasis mine).
>>
>> Turns out this only works when the first value is numeric and not NA, as
>> shown by the following example:
>>
>> > sprintf("%d", as.numeric(c(NA,1)))
>> Error in sprintf("%d", as.numeric(c(NA, 1))) :
>>   invalid format '%d'; use format %f, %e, %g or %a for numeric objects
>> > sprintf("%d", as.numeric(c(1,NA)))
>> [1] "1"  "NA"
>>
>> So the safest thing is indeed passing the right type, but the behaviour
>> is indeed confusing. I checked this on both Windows and Debian, and on both
>> systems I get the exact same response.
>>
>> Cheers
>> Joris
>>
>> On Tue, May 23, 2017 at 4:53 PM, Evan Cortens <ecortens at mtroyal.ca>
>> wrote:
>>
>>> Hi Michael,
>>>
>>> I posted something on this topic to R-devel several weeks ago, but never
>>> got a response. My ultimate conclusion is that sprintf() isn't super
>>> consistent in how it handles coercion: sometimes it'll coerce real to
>>> integer without complaint, other times it won't. (My particular email had
>>> to do with the vectors longer than 1 and their positioning vis-a-vis the
>>> format string.) The safest thing is just to pass the right type. In this
>>> case, sprintf('%d', as.integer(NA_real_)) works.
>>>
>>> Best,
>>>
>>> Evan
>>>
>>> On Fri, May 19, 2017 at 9:23 AM, Michael Chirico <
>>> michaelchirico4 at gmail.com>
>>> wrote:
>>>
>>> > Consider
>>> >
>>> > #as.numeric for emphasis
>>> > sprintf('%d', as.numeric(1))
>>> > # [1] "1"
>>> >
>>> > vs.
>>> >
>>> > sprintf('%d', NA_real_)
>>> >
>>> > >  Error in sprintf("%d", NA_real_) :
>>> >
>>> >    invalid format '%d'; use format %f, %e, %g or %a for numeric object
>>> > >
>>> >
>>> > I understand the error is correct, but if it works for other numeric
>>> input,
>>> > why doesn't R just coerce NA_real_ to NA_integer_?
>>> >
>>> > Michael Chirico
>>> >
>>> >         [[alternative HTML version deleted]]
>>> >
>>> > ______________________________________________
>>> > R-devel at r-project.org mailing list
>>> > https://stat.ethz.ch/mailman/listinfo/r-devel
>>> >
>>>
>>>
>>>
>>> --
>>> Evan Cortens, PhD
>>> Institutional Analyst - Office of Institutional Analysis
>>> Mount Royal University
>>> 403-440-6529
>>>
>>>         [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-devel at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>>
>>
>>
>>
>> --
>> Joris Meys
>> Statistical consultant
>>
>> Ghent University
>> Faculty of Bioscience Engineering
>> Department of Mathematical Modelling, Statistics and Bio-Informatics
>>
>> tel :  +32 (0)9 264 61 79 <+32%209%20264%2061%2079>
>> Joris.Meys at Ugent.be
>> -------------------------------
>> Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php
>>
>
>

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