larry-discuss team mailing list archive

[josef.pktd@xxxxxxxxx]

On Fri, Feb 5, 2010 at 1:05 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
> On Fri, Feb 5, 2010 at 10:03 AM,  <josef.pktd@xxxxxxxxx> wrote:
>> On Fri, Feb 5, 2010 at 12:56 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>> On Fri, Feb 5, 2010 at 9:48 AM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>>> On Fri, Feb 5, 2010 at 9:37 AM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>>>> On Fri, Feb 5, 2010 at 9:19 AM,  <josef.pktd@xxxxxxxxx> wrote:
>>>>>> On Fri, Feb 5, 2010 at 12:01 PM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>>>>>> On Fri, Feb 5, 2010 at 8:52 AM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>>>>>>> On Fri, Feb 5, 2010 at 7:28 AM, Keith Goodman <kwgoodman@xxxxxxxxx> wrote:
>>>>>>>>> On Fri, Feb 5, 2010 at 7:24 AM,  <josef.pktd@xxxxxxxxx> wrote:
>>>>>>>>>> The current signature
>>>>>>>>>>
>>>>>>>>>> assert_larry_equal(actual, desired, msg='', dtype=True, original=None,
>>>>>>>>>>                       noreference=True, nocopy=False)
>>>>>>>>>>
>>>>>>>>>> has 3 keywords, original, noreference, nocopy for the option to check
>>>>>>>>>> whether a larry is a view or a copy.
>>>>>>>>>>
>>>>>>>>>> This makes 8 binary options, only 3 are relevant cases, the other 5
>>>>>>>>>> combinations raise errors or are redundant. This was quite confusing
>>>>>>>>>> when I used the tests, since I often forgot to use, reset a keyword,
>>>>>>>>>> e.g. nocopy=True also requires setting noreference = False
>>>>>>>>>>
>>>>>>>>>> I think a more compact signature would be
>>>>>>>>>> assert_larry_equal(actual, desired, msg='', dtype=True, original=None,
>>>>>>>>>> noref=True)
>>>>>>>>>>
>>>>>>>>>> if not original is None:
>>>>>>>>>>    if noref:
>>>>>>>>>>       check noreference
>>>>>>>>>>    else:
>>>>>>>>>>       check nocopy
>>>>>>>>>>
>>>>>>>>>> otherwise don't do any reference/copy check
>>>>>>>>>>
>>>>>>>>>> the presence of original would indicate that we want the view check,
>>>>>>>>>> `noref` would tell which one.
>>>>>>>>>
>>>>>>>>> This is how larry gets improved---with cleaning like that.
>>>>>>>>>
>>>>>>>>> I'll make the change in the trunk.
>>>>>>>>
>>>>>>>> I changed the function signature as you suggested. I also changed
>>>>>>>> noref to iscopy. The change in the kw name will mess up your unit
>>>>>>>> tests :(
>>>>>>
>>>>>> I will change them
>>>>>>
>>>>>>>>
>>>>>>>> And I change the name of assert_noreference to assert_iscopy and
>>>>>>>> assert_nocopy to assert_isview.
>>>>>>>
>>>>>>> Here's a potential problem if the label contains objects:
>>>>>>>
>>>>>>>>> import datetime
>>>>>>>>> x = larry([1, 2] , [[9, datetime.date(2009,1,1)]])
>>>>>>>>> y = larry([1, 2] , [[7, x.label[0][1]]])
>>>>>>>>> x.label[0][1] is y.label[0][1]
>>>>>>>   True
>>>>>>>>> la.util.testing.assert_iscopy(x, y)
>>>>>>>>>
>>>>>>>
>>>>>>> assert_iscopy and assert_isview only compare the entire axis at once:
>>>>>>>
>>>>>>>    for i in xrange(larry1.ndim):
>>>>>>>        if larry1.label[i] is larry2.label[i]:
>>>>>>>            msg.append('The labels along axis %d share a reference.' % i)
>>>>>>>
>>>>>>> So I should change that to loop over each label element, right?
>>>>>>
>>>>>> Yes. Because this is for the tests, we want to catch all cases, even
>>>>>> if they don't show up in common usage.
>>>>>>
>>>>>> Do we have the same problem with nested labels, e.g. tuples after
>>>>>> flatten?  Maybe then a recursive helper function is useful.
>>>>>
>>>>> Now I know why I didn't check each label element:
>>>>>
>>>>>>>> 9 is 9
>>>>> True
>>>>>
>>>>> So I need to check if the object is immutable. Do you know how to do
>>>>> that? A tuple is immutable, but not the elements inside. Seems
>>>>> complicated.
>>>>
>>>> I'm only comparing, or trying to compare, label elements that are in
>>>> the same position in both larrys. I guess label element i along axis j
>>>> in larry1 should instead be compared to all label elements in larrys2
>>>> to search for references. That might actually be easier to code. We'd
>>>> need a function that collapses tuples and lists into a single list and
>>>> then do all cross comparisons. The unit test larrys are small so it
>>>> should not take long. And after comparing i with j we wouldn't need to
>>>> compare j to i.
>>>
>>> Ack! This is too complicated. And I don't see much gain from it. Plus
>>> the copylabel method in larry looks pretty solid:
>>>
>>>    def copylabel(self):
>>>        """
>>>        Return a copy of a larry's label.
>>>
>>>        Examples
>>>        --------
>>>        >>> y = larry([1, 2], [['a', 'b']])
>>>        >>> label = y.copylabel()
>>>        >>> label
>>>        [['a', 'b']]
>>>
>>>        """
>>>        return deepcopy(self.label)
>>>
>>> So I'm thinking of leaving assert_iscopy and assert_isview as is. So
>>> only check if an entire axis is a label copy.
>>>
>>> If we were to keep going with this we'd realize that the exact same
>>> issue applies to the data array in larry:
>>>
>>>>> x = np.array([1, datetime.date(2009,1,1)])
>>>>> y = np.array([2, x[1]])
>>>>> x[1] is y[1]
>>>   True
>>>>> x is y
>>>   False
>>>
>>> So a full comparison is needed there too.
>>
>> No, for numpy arrays we have the array methods, and there are stronger
>> memory restrictions. When we compare larrys that are produced by
>> slicing then we would need to check the base attribute of the array,
>> we wouldn't check individual array elements.  Although, I'm not
>> completely sure this holds for object arrays.
>
> But doesn't the example below fail?
>
>>>>> x = np.array([1, datetime.date(2009,1,1)])
>>>>> y = np.array([2, x[1]])
>>>>> x[1] is y[1]
>>>   True
>>>>> x is y
>>>   False
>

it looks like datetime.dates are like "2 is 2"

>>> x = np.array([1, datetime.date(2009,1,1)]); y = np.array([2, x[1]])
>>> y
array([2, 2009-01-01], dtype=object)
>>> x[1] = 5
>>> y
array([2, 2009-01-01], dtype=object)

y is a copy