Re: [Pytables-users] Column gets updated but table does not reflect

[Alvaro T. C. <al...@mi...>]

Ok, I think I know what happened: during interactive manipulation, at
some point I must have forgotten adding '[:]' to assign to the column,
i.e.

mytable.cols.mycolumn = somearray

instead of

mytable.cols.mycolumn[:] = somearray

This is related to

https://github.com/PyTables/PyTables/issues/145

In-memory assignments can shadow access to the object in the file.
IMHO this should not be allowed (in, fact, why not making the first
assignment behave like the second?).

-á.


On Mon, Apr 30, 2012 at 20:24, Alvaro Tejero Cantero <al...@mi...> wrote:
> I am now on another computer (no access to the one where I reported
> the problem until tomorrow; uses 2.3.1 AFAIK) and here I have the
> expected behaviour (2.3.1, as well). I hope that I made a mistake;
> will update tomorrow.
>
>
> -á.
>
>
> On Mon, Apr 30, 2012 at 20:09, Francesc Alted <fa...@py...> wrote:
>> On 4/30/12 12:08 PM, Alvaro Tejero Cantero wrote:
>>> Hi all,
>>>
>>> I created a table:
>>>
>>>>>> joins.createTable('/','spikes',{'t20k':pt.Int32Col(),'tetrode':pt.UInt8Col(), 'unit':pt.UInt8Col()},'Spike times')
>>> I populated it
>>>
>>>>>> joins.root.spikes.append(zip(np.arange(100),np.zeros(100), 3*np.ones(100)))
>>> now if I do
>>>
>>>>>> joins.root.spikes.cols.tetrode[:] = np.ones(100)
>>> I can see the updated value (all ones instead of zeros)
>>>
>>> If I fetch all the table in memory,
>>>
>>>>>> joins.root.spikes[:]
>>> I still see only the original zeros, i.e. the column update has not propagated
>>
>> Hmm, I cannot reproduce this:
>>
>> In [18]: joins = pt.openFile("joins.h5", "w")
>>
>> In [19]:
>> joins.createTable('/','spikes',{'t20k':pt.Int32Col(),'tetrode':pt.UInt8Col(),
>> 'unit':pt.UInt8Col()},'Spike times')
>> Out[19]:
>> /spikes (Table(0,)) 'Spike times'
>>   description := {
>>   "t20k": Int32Col(shape=(), dflt=0, pos=0),
>>   "tetrode": UInt8Col(shape=(), dflt=0, pos=1),
>>   "unit": UInt8Col(shape=(), dflt=0, pos=2)}
>>   byteorder := 'little'
>>   chunkshape := (10922,)
>>
>> In [20]: joins.root.spikes.append(zip(np.arange(10),np.zeros(10),
>> 3*np.ones(10)))
>>
>> In [22]: joins.root.spikes[:]
>> Out[22]:
>> array([(0, 0, 3), (1, 0, 3), (2, 0, 3), (3, 0, 3), (4, 0, 3), (5, 0, 3),
>>        (6, 0, 3), (7, 0, 3), (8, 0, 3), (9, 0, 3)],
>>       dtype=[('t20k', '<i4'), ('tetrode', 'u1'), ('unit', 'u1')])
>>
>> In [23]: joins.root.spikes.cols.tetrode[:] = np.ones(10)
>>
>> In [24]: joins.root.spikes[:]
>> Out[24]:
>> array([(0, 1, 3), (1, 1, 3), (2, 1, 3), (3, 1, 3), (4, 1, 3), (5, 1, 3),
>>        (6, 1, 3), (7, 1, 3), (8, 1, 3), (9, 1, 3)],
>>       dtype=[('t20k', '<i4'), ('tetrode', 'u1'), ('unit', 'u1')])
>>
>> Which versions are you using?
>>
>> --
>> Francesc Alted
>>
>>
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