Re: [Pytables-users] `__iter__` state and `itertools.islice` when
Hi Tony,
Il giorno 09/lug/2013, alle ore 06:38, Tony Yu tsy...@gmail.com ha scritto:
Hi,
I ran into a subtle, unexpected issue while using `itertools.islice`. I
wanted to pass slices of an array for processing without actually reading the
entire array, and I wanted that processing function to know nothing about how
I'm taking that slice. To that end, I had a loop that sliced the array using
`itertools.islice` and called the function on each slice. Instead of
returning the slice I specified, `islice` treated the previous end slice as
the starting point to the next slice.
That description is a bit confusing, but the example below (along with the
attached test data) should illustrate the point. Maybe I'm missing something,
but the only work around that I found was to set a private flag (e.g.
`h5.root.array._init = False`) on each call to `islice` to reset the counter
used in `__iter__`.
I'm not sure if this is expected behavior or not, but it does differ from how
`islice` works on numpy arrays (as demonstrated in the example below). I used
the google and nothing similar came up, so I thought I'd post here.
Best,
-Tony
#
import tables
import itertools
import numpy as np
h5 = tables.openFile('test.h5')
array = np.arange(100)
for i in range(5):
# Numpy array slice always returns 0..10
print list(itertools.islice(array, 0, 10))
# PyTables array slice shifts with each iteration
print list(itertools.islice(h5.root.array, 0, 10))
h5.close()
test.h5--
Yes, this is a bug IMO.
Thank you for reporting and thank you for the small demonstration script.
Can you please file a bug report on github [1]?
Please also add info about the PyTables version you used for the test..
[1] https://github.com/PyTables/PyTables/issues
--
Antonio Valentino
--
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Re: [Pytables-users] `__iter__` state and `itertools.islice` when
On Tue, Jul 9, 2013 at 12:58 AM, Antonio Valentino antonio.valent...@tiscali.it wrote: snip Yes, this is a bug IMO. Thank you for reporting and thank you for the small demonstration script. Can you please file a bug report on github [1]? Please also add info about the PyTables version you used for the test.. Thanks for you quick reply. Ticket filed here: https://github.com/PyTables/PyTables/issues/267 Best, -Tony [1] https://github.com/PyTables/PyTables/issues -- Antonio Valentino -- See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831iu=/4140/ostg.clktrk___ Pytables-users mailing list Pytables-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/pytables-users
Re: [Pytables-users] `__iter__` state and `itertools.islice` when
On Tue, Jul 9, 2013 at 8:57 AM, Tony Yu tsy...@gmail.com wrote: On Tue, Jul 9, 2013 at 12:58 AM, Antonio Valentino antonio.valent...@tiscali.it wrote: snip Yes, this is a bug IMO. Thank you for reporting and thank you for the small demonstration script. Can you please file a bug report on github [1]? Please also add info about the PyTables version you used for the test.. Thanks for you quick reply. Ticket filed here: https://github.com/PyTables/PyTables/issues/267 Thanks Tony, I have made my comments on the issue, but the short version is that I don't think this is a bug, iteration needs a rewrite, and you should use iterrows(). Be Well Anthony PS you should upgrade to 3.0 and use the new API :) Best, -Tony [1] https://github.com/PyTables/PyTables/issues -- Antonio Valentino -- See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831iu=/4140/ostg.clktrk ___ Pytables-users mailing list Pytables-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/pytables-users -- See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831iu=/4140/ostg.clktrk___ Pytables-users mailing list Pytables-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/pytables-users
