On 25/02/11 18:59, Artur Wroblewski wrote:
> On Fri, Feb 25, 2011 at 5:25 PM, Laurent<lgaut...@gmail.com> wrote:
>> On 24/02/11 11:26, Artur Wroblewski wrote:
> [...]
>>> In Python
>>>
>>> >>> (1, None, 2, None, 3)
>>> (1, None, 2, None, 3)
>>>
>>> In R
>>>
>>> > c(1, NULL, 2, NULL, 3)
>>> [1] 1 2 3<- NULL is removed, by default
>>>
>>> > c(1, NA, 2, NA, 3)
>>> [1] 1 NA 2 NA 3<- NA is kept, by default
>>
>>
>> There are places where some people can see R as counter-intuitive, and I
>> think that this is one such place. Although Python-None seems closer to
>> C-Null and R-NULL, the behaviour you describe is what made me have None in
>> the list passed to the constructor raise an exception: better explicit than
>> implicit when confusion can occur.
>> Rather than None, one should be using one of the
>> rpy2.rinterface.NA_<whatever>.
>
> I assume, that while using Python, in his/her code, everyone is going to use
> None.
I am not sure about that. I believe that generally one would populate a
list built in upstream code what they think will be useful in downstream
code (here a call to a constructor for <Whatever>Vector).
I do no understand why rpy cannot change None to NA during
> conversion to a vector (by default or with some parameter).
Because None is conceptually closer to Python-NULL and C-Null, rather
than the idea of a missing value (that point of view seems to be, at
least in parts, shared by array and numpy)
>>> import array
>>> array.array('i', (1, None, 3))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: an integer is required
Cheers,
Laurent
> Best regards,
>
> Artur
>
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