larry-discuss team mailing list archive

[Keith Goodman <kwgoodman@xxxxxxxxx>]

On Fri, Feb 5, 2010 at 10:10 AM,  <josef.pktd@xxxxxxxxx> wrote:
> 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"

But not exactly alike:

>> datetime.date(2001,1,1) is datetime.date(2001,1,1)
   False

>>>> 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

Excellent! Yes, that is the true test.