#18269: A new structure for experimentation on decoding: communication channels
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Reporter: | Owner:
dlucas | Status: needs_info
Type: | Milestone: sage-6.7
enhancement | Resolution:
Priority: major | Merged in:
Component: | Reviewers:
coding theory | Work issues:
Keywords: | Commit:
Authors: | 5f31c5cef52b9b0bdbd905f4ff132e344446e766
Report Upstream: N/A | Stopgaps:
Branch: |
u/dlucas/channels |
Dependencies: |
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Comment (by vdelecroix):
Replying to [comment:7 dlucas]:
> I did some changes, as stated by commit messages above.
>
> Some remarks:
>
> - I kept `tuple_to_integer` because the user can pass either an integer
or an
> interval as `number_errors` parameter for the channels. If the user
passes an
> integer, then `randint` won't work. Of course it is possible to do the
check
> anytime you call `number_errors` (if integer, return it, else do a
randint
> and return the result) but it's rather tedious. Especially because it's
> something that will be used by a some channels. I think it's easier to
call a
> single method rather than copying the `if` statement each time. Maybe
> `tuple_to_integer` is not really a good name though.
The name is very bad. Moreover you can convert an integer `a` into the
tuple `(a,a)` in the constructor. With your way of doing it you avoid the
function call to `randint` but with your version you always add an extra
function call to `tuple_to_integer`.
You should replace all occurrence of `hasattr(X, '__iter__')` by
`isinstance(X, (tuple, list))`. Having an `__iter__` method does not
charaterize tuples.
> - `random_error_vector(n, F, error_positions)` returns a vector of
length `n`
> over `F` with `0`s in every position except those listed in
> `error_positions`. Because of this, calling `vect = [F.random_element()
for _
> in range(n)]` in `random_error_vector` does not really fit, because it
will
> create a vector with non-controlled zero positions, so we'll need to set
all
> positions except those into `error_positions` afterwards. I think create
a
> zero vector of size `n` and add random values at some positions is
better.
Yes. You are right!
> - I did not change the documentation, nor the catalog stuff (see comment
4).
> If you think that Channels are actually more linked to codes than to
anything
> else, I can make some changes
You should tell me ;-) Cryptogtaphers might like it but they do use
strings
not vectors in a vector space over a finite field.
12. When you do `__call__ = transmit` the documentation is copied as well.
Did you try
{{{
sage: Chan = channels.StaticErrorRateChannel(GF(11), 2)
sage: Chan.__call__?
}}}
13. I would rather implement `StaticErrorRateChannel.transmit_unsafe` as
{{{
def transmit_unsafe(self, msg):
w = msg.copy()
V = self.input_space()
for i in sample_range(V.dim(), randint(*self.nb_errors())):
w[i] = V.random_element()
return w
}}}
it would be more direct. Moreover it shows that `sample_range` would
better be an iterator instead of returning a list. By the way, this
function `sample_range` has currently linear complexity in `n`, isn't it
possible to make it linear in `k`?
14. In the main documentation class, it is useful to document the main
methods. In other words, when reading {{{sage:
channels.StaticErrorChannel?}}} I should be able to discvoer the method
`transmit` (and its alias usage with `__call__`).
15. In the very top documentation, you can have links by writing
{{{class:`AbstractChannel`}}} instead of {{{*AbstractChannel*}}}.
Vincent
--
Ticket URL: <http://trac.sagemath.org/ticket/18269#comment:10>
Sage <http://www.sagemath.org>
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