[Python-ideas] Re: Addition to fnmatch.py
On Tue, 7 Jun 2022 at 10:26, Steven D'Aprano wrote: > > Why don't you use the version from the itertools recipes? > > > ``` > from itertools import tee, filterfalse > def partition(pred, iterable): > "Use a predicate to partition entries into false entries and true entries" > # partition(is_odd, range(10)) --> 0 2 4 6 8 and 1 3 5 7 9 > t1, t2 = tee(iterable) > return filterfalse(pred, t1), filter(pred, t2) > ``` > > Calls the predicate twice for every element, so it's only good for a guaranteed-deterministic predicate. You may want to read the thread before responding. ChrisA ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/NS6ORDJ4STDGOJID5B5NQXZ4MVC5QORQ/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Addition to fnmatch.py
Why don't you use the version from the itertools recipes? ``` from itertools import tee, filterfalse def partition(pred, iterable): "Use a predicate to partition entries into false entries and true entries" # partition(is_odd, range(10)) --> 0 2 4 6 8 and 1 3 5 7 9 t1, t2 = tee(iterable) return filterfalse(pred, t1), filter(pred, t2) ``` -- Steve ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/TOQKBCZNXZRH5BVFPPFOPJTVPA3KOZ54/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Addition to fnmatch.py
On Mon, Jun 06, 2022 at 06:17:32PM +0200, Benedict Verhegghe wrote: > There still is something wrong. I get the second list twice: > > odd, even = partition(lambda i: i % 2, range(20)) > print(list(odd)) > [1, 3, 5, 7, 9, 11, 13, 15, 17, 19] > print(list(even)) > [0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18] Confirmed. But if you replace range(20) with `iter(range(20))`, it works correctly. The plot thickens. The duplicated list is not from the second list created, but the second list *evaluated*. So if you run: odd, even = partition(...) as before, but evaluate *even* first and odd second: print(list(even)) print(list(odd)) it is odd that is doubled, not even. -- Steve ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/OJIA6HIH6UJYE7X7LU7W46QI2X6UPTK6/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Add .except() and .only(), and .values_at(). instance methods to dict
This idea reminds me of numpy fancy indexing: that is, you can pass
multiple indexes in at once. (See bumpy docs for details). I have no idea
how that might translate to ducts (tulles are perfectly reasonable keys
already) but I know I like it in numpy :-)
That being said, I can’t remember a use case where I would have used it
with dicts.
-CHB
On Mon, Jun 6, 2022 at 11:04 AM Chris Angelico wrote:
> On Mon, 6 Jun 2022 at 18:02, Stephen J. Turnbull
> wrote:
> >
> > David Mertz, Ph.D. writes:
> >
> > > These are all far too easy to do with comprehensions to merit new
> methods
> > > or stdlib functions.
> >
> > +1
> >
> > > E.g., we might provide additional set-like operators for dicts.
> >
> > > >>> m - {'a'} # Would rightval be a set or dict though?!
> > > >>> m & {'a', 'b'} # Same question, but set feels better, I think
> >
> > Why not "either"? Of course if you allow dicts, the question in both
> > cases becomes whether the presence test is on keys or items. I think
> > keys would be more frequently useful.
> >
>
> Or even: Any iterable that yields keys? And then the presence test
> would be defined entirely by keys (which makes the most sense). You
> could subtract another dict, or a set, list, or anything.
>
> (You could even subtract the string "ab" to remove keys "a" and "b",
> for what it's worth.)
>
> Of note: https://peps.python.org/pep-0584/#what-about-the-full-set-api
>
> """This PEP does not take a position on whether dicts should support
> the full collection of set operators, and would prefer to leave that
> for a later PEP (one of the authors is interested in drafting such a
> PEP)."""
>
> So if you (or anyone) wants to move forward with this, I would
> recommend (a) reading the notes in PEP 584, (b) reaching out to all
> three authors of it to find out their current sentiment, and (c)
> designing definitive semantics for the operators in question. I'd be
> happy to help with the mechanics of getting a PEP written.
>
> ChrisA
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--
Christopher Barker, PhD (Chris)
Python Language Consulting
- Teaching
- Scientific Software Development
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[Python-ideas] Re: Addition to fnmatch.py
On Tue, 7 Jun 2022 at 01:58, David Mertz, Ph.D. wrote: > In [2]: def isEven(n): >...: return n/2 == n//2 >...: > Huh. That's a very strange way to write that predicate. >>> isEven(2) True >>> isEven(20001) True >>> isEven(20002) False >>> isEven(20003) False >>> isEven(20004) True Why not just "return n % 2 == 0" ? ChrisA ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/HDNXSZI24RIMJDHWOMPIWQXN4EZUA4Y3/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Addition to fnmatch.py
Op 6/06/2022 om 18:07 schreef Mathew Elman: oops, you're right, I have ended up with an unnecessary "not" in there, should be: from collections import deque def partition(pred, iterable): results = deque([]), deque([]) def gen_split(only): for thing in iterable: if results[only]: yield results[only].popleft() results[pred(thing)].append(thing) for thing in results[only]: yield thing return gen_split(True), gen_split(False) There still is something wrong. I get the second list twice: odd, even = partition(lambda i: i % 2, range(20)) print(list(odd)) [1, 3, 5, 7, 9, 11, 13, 15, 17, 19] print(list(even)) [0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18] ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/JYGSSXPN6FLGHVJPUM4XTPH2EABZZMLS/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Addition to fnmatch.py
oops, you're right, I have ended up with an unnecessary "not" in there, should be: from collections import deque def partition(pred, iterable): results = deque([]), deque([]) def gen_split(only): for thing in iterable: if results[only]: yield results[only].popleft() results[pred(thing)].append(thing) for thing in results[only]: yield thing return gen_split(True), gen_split(False) ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/QURICBHMB3D2WG2VWEBJ56Q6ZZHKBUJX/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Addition to fnmatch.py
This is really nice, but I think you have a negation wrong in there somewhere: In [1]: from collections import deque ...: ...: def partition(pred, iterable): ...: results = deque([]), deque([]) ...: ...: def gen_split(only): ...: for thing in iterable: ...: if results[only]: ...: yield results[only].popleft() ...: results[not pred(thing)].append(thing) ...: for thing in results[only]: ...: yield thing ...: ...: return gen_split(True), gen_split(False) ...: In [2]: def isEven(n): ...: return n/2 == n//2 ...: In [3]: from itertools import count In [4]: evens, odds = partition(isEven, count()) In [5]: next(evens) Out[5]: 1 In [6]: next(evens) Out[6]: 3 In [7]: next(evens) Out[7]: 5 In [8]: next(odds) Out[8]: 0 In [9]: next(odds) Out[9]: 2 In [10]: next(odds) Out[10]: 4 On Mon, Jun 6, 2022 at 10:32 AM Mathew Elman wrote: > from collections import deque > > def partition(pred, iterable): > results = deque([]), deque([]) > > def gen_split(only): > for thing in iterable: > if results[only]: > yield results[only].popleft() > results[not pred(thing)].append(thing) > for thing in results[only]: > yield thing > > return gen_split(True), gen_split(False) > ___ > Python-ideas mailing list -- python-ideas@python.org > To unsubscribe send an email to python-ideas-le...@python.org > https://mail.python.org/mailman3/lists/python-ideas.python.org/ > Message archived at > https://mail.python.org/archives/list/python-ideas@python.org/message/EUAYPXMZM4DOGTAAUURNOMWTDU65K6UY/ > Code of Conduct: http://python.org/psf/codeofconduct/ > -- Keeping medicines from the bloodstreams of the sick; food from the bellies of the hungry; books from the hands of the uneducated; technology from the underdeveloped; and putting advocates of freedom in prisons. Intellectual property is to the 21st century what the slave trade was to the 16th. ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/HWKJMLZSQVZQERYAKYZUAMK2YGIFUPIX/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Addition to fnmatch.py
Thanks for all the comments. I did consider using sets but order was important and when partitioning a list of general strings, not file names, there could be identical and important strings (strings at different positions could mean different things, especially when generating test and training sets). I also tried doing it twice (generating lists) and it took approximately twice as long though generating two iterables could defer the partitioning till it was needed, i.e. lazy evaluation. I’ve added some of the solutions to by timing test. Identified by capital letters at the end. Reference list lengths 144004 855996 Number of tests cases 100 Example data ['xDy7AWbXau', 'TXlzsZV3Ra', 'YJh8uD9ovK', 'aRJ2U7nWs8', 'geu.vHlogu'] FNmatch0.671875 268756 0 2687560 WCmatch1.562500 264939 0 2649390 IWCmatch 1.281250 0 0 01 Easy 0.093750 144004 855996 1001 Re 0.328125 855996 144004 1000 Positive 0.281250 144004 0 1440041 Negative 0.328125 0 855996 8559961 UppeeCase 0.375000 268756 0 2687560 Null 0.00 0 0 01 Both 0.328125 144004 855996 1001 Partition 1.171875 855996 144004 1000 IBoth 0.328125 855996 144004 1000 MRAB 0.437500 144004 855996 1001 METZ 0.50 144004 855996 1001 CA 0.343750 144004 855996 1001 SJB0.328125 144004 855996 1001 I checked for order and interestingly all the set solutions preserve it. I think this is because there are no duplicates in the test data. Order is only checked correctly if thee are the same number of elements in the test and reference lists I also tried more_itertoolls.partition. Nearly 4 times slower. John ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/6WFSIXUF67KU5QXOODCBG7RDDG2KSYSK/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Addition to fnmatch.py
from collections import deque def partition(pred, iterable): results = deque([]), deque([]) def gen_split(only): for thing in iterable: if results[only]: yield results[only].popleft() results[not pred(thing)].append(thing) for thing in results[only]: yield thing return gen_split(True), gen_split(False) ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/EUAYPXMZM4DOGTAAUURNOMWTDU65K6UY/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Addition to fnmatch.py
As Chris Angelico notes, that's only good for finite iterables. The recipe in the itertools docs is unbounded, but it's also unbounded in the cache needed if you get long strings of things the do (or don't) confirm the predicate. On Mon, Jun 6, 2022 at 7:06 AM Stephen J. Turnbull < stephenjturnb...@gmail.com> wrote: > Christopher Barker writes: > > > How do you divide a sequence into two sequences cleanly? > > I don't know how to do it in a one liner, but > > yes = [] > no = [] > for elem in seq: > (yes if test(elem) else no).append(elem) > > seems pretty clean to me. > > ___ > Python-ideas mailing list -- python-ideas@python.org > To unsubscribe send an email to python-ideas-le...@python.org > https://mail.python.org/mailman3/lists/python-ideas.python.org/ > Message archived at > https://mail.python.org/archives/list/python-ideas@python.org/message/BBVBDT7KJTTOD5VQYIHBCQBU5QV32ZUB/ > Code of Conduct: http://python.org/psf/codeofconduct/ > -- Keeping medicines from the bloodstreams of the sick; food from the bellies of the hungry; books from the hands of the uneducated; technology from the underdeveloped; and putting advocates of freedom in prisons. Intellectual property is to the 21st century what the slave trade was to the 16th. ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/4RIL6JUJXJDF3G6HWVU4DD33TKPEZYCI/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Addition to fnmatch.py
Christopher Barker writes: > How do you divide a sequence into two sequences cleanly? I don't know how to do it in a one liner, but yes = [] no = [] for elem in seq: (yes if test(elem) else no).append(elem) seems pretty clean to me. ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/BBVBDT7KJTTOD5VQYIHBCQBU5QV32ZUB/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Addition to fnmatch.py
On Mon, 6 Jun 2022 at 18:22, Paul Moore wrote: > > There’s an itertools recipe, “partition”. > Yes, there is (and plenty of equivalents in other languages). But it's still not what I'd call "particularly easy". What that recipe does is filter the same iterable with the same predicate twice, so it depends on the predicate being repeatable. You can't use it, for instance, to split a data set into training and test sets, even though conceptually this should work: training, test = partition(lambda x: random.random() < 0.9, dataset) To truly perform a one-pass partitioning operation, you'd have to do something like this: def partition(pred, iter): results = [], [] for thing in iter: results[not pred(thing)].append(thing) return results Obviously that works only on finite iterables, so it's not appropriate for an itertools recipe, but it does guarantee that the predicate is called once per item and each item ends up in precisely one list. It would be kinda nice to be able to do something like this with a comprehension, since there's a fair bit of overhead to calling a function (predicate functions have to be called for each element, but a comprehension wraps everything up into one function). But since it's not, the above is good enough for the cases where it's needed - not particularly easy, but not all that hard either. ChrisA ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/BUFIMKKIJOPJQQ4WT2VLNXTTLAPQGCIN/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Add .except() and .only(), and .values_at(). instance methods to dict
On Mon, 6 Jun 2022 at 18:02, Stephen J. Turnbull
wrote:
>
> David Mertz, Ph.D. writes:
>
> > These are all far too easy to do with comprehensions to merit new methods
> > or stdlib functions.
>
> +1
>
> > E.g., we might provide additional set-like operators for dicts.
>
> > >>> m - {'a'} # Would rightval be a set or dict though?!
> > >>> m & {'a', 'b'} # Same question, but set feels better, I think
>
> Why not "either"? Of course if you allow dicts, the question in both
> cases becomes whether the presence test is on keys or items. I think
> keys would be more frequently useful.
>
Or even: Any iterable that yields keys? And then the presence test
would be defined entirely by keys (which makes the most sense). You
could subtract another dict, or a set, list, or anything.
(You could even subtract the string "ab" to remove keys "a" and "b",
for what it's worth.)
Of note: https://peps.python.org/pep-0584/#what-about-the-full-set-api
"""This PEP does not take a position on whether dicts should support
the full collection of set operators, and would prefer to leave that
for a later PEP (one of the authors is interested in drafting such a
PEP)."""
So if you (or anyone) wants to move forward with this, I would
recommend (a) reading the notes in PEP 584, (b) reaching out to all
three authors of it to find out their current sentiment, and (c)
designing definitive semantics for the operators in question. I'd be
happy to help with the mechanics of getting a PEP written.
ChrisA
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[Python-ideas] Re: Efficiency of set difference
06.06.22 10:51, Stephen J. Turnbull пише: Couldn't it be linear on min(len(left), len(right))? Ie, if len(left) < len(right): for elem in left: if elem in right: left.discard(elem) else: for elem in right: left.discard(elem) The upper loop is probably only about half as fast as the lower (two hashes needed), so maybe the length test could be tuned. The whole idea is probably not worth it, I can't think of practical use cases at a scale where it would matter. It is close to the current implementation: if len(left) < len(right)//8: right = left & right for elem in left: if elem in right: left.discard(elem) ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/OGOMGS4353C34REIWQWWUNPF6LAX655C/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Addition to fnmatch.py
There’s an itertools recipe, “partition”. On Mon, 6 Jun 2022 at 08:28, Chris Angelico wrote: > On Mon, 6 Jun 2022 at 16:42, Christopher Barker > wrote: > > > > I think y’all have addressed the OP’s problem — at least the performance > issues. > > > > But I think this brings up a pattern that I don’t have a nifty way to > address: > > > > How do you divide a sequence into two sequences cleanly? > > > > The filter pattern: selectively remove items from a sequence, returning > a new sequence. There are a few ways to do that in Python. > > > > But what if you need both the remaining items and the removed ones? Easy > enough to write a loop that populates two lists, but is there a nifty > one-liner? > > > > Is this a known functional pattern? > > > > I'd call that a "partitioning" task, and you're right, it's not > particularly easy in Python. > > ChrisA > ___ > Python-ideas mailing list -- python-ideas@python.org > To unsubscribe send an email to python-ideas-le...@python.org > https://mail.python.org/mailman3/lists/python-ideas.python.org/ > Message archived at > https://mail.python.org/archives/list/python-ideas@python.org/message/NEY4JKQMDTMS6PN3I6VK6FCICRLCG43P/ > Code of Conduct: http://python.org/psf/codeofconduct/ > ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/7TFCBUT6UD67UVYNUUTKUP26A5FGSUDO/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Add .except() and .only(), and .values_at(). instance methods to dict
David Mertz, Ph.D. writes:
> These are all far too easy to do with comprehensions to merit new methods
> or stdlib functions.
+1
> E.g., we might provide additional set-like operators for dicts.
> >>> m - {'a'} # Would rightval be a set or dict though?!
> >>> m & {'a', 'b'} # Same question, but set feels better, I think
Why not "either"? Of course if you allow dicts, the question in both
cases becomes whether the presence test is on keys or items. I think
keys would be more frequently useful.
Steve
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[Python-ideas] Efficiency of set difference
David Mertz, Ph.D. writes:
> This is exactly the problem solved by set difference. E.g.
> `{a, b, c} - {a, c}`.
>
> This operation is linear on the size of the removed set.
Couldn't it be linear on min(len(left), len(right))? Ie,
if len(left) < len(right):
for elem in left:
if elem in right:
left.discard(elem)
else:
for elem in right:
left.discard(elem)
The upper loop is probably only about half as fast as the lower (two
hashes needed), so maybe the length test could be tuned.
The whole idea is probably not worth it, I can't think of practical
use cases at a scale where it would matter.
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[Python-ideas] Re: Addition to fnmatch.py
On Mon, 6 Jun 2022 at 16:42, Christopher Barker wrote: > > I think y’all have addressed the OP’s problem — at least the performance > issues. > > But I think this brings up a pattern that I don’t have a nifty way to address: > > How do you divide a sequence into two sequences cleanly? > > The filter pattern: selectively remove items from a sequence, returning a new > sequence. There are a few ways to do that in Python. > > But what if you need both the remaining items and the removed ones? Easy > enough to write a loop that populates two lists, but is there a nifty > one-liner? > > Is this a known functional pattern? > I'd call that a "partitioning" task, and you're right, it's not particularly easy in Python. ChrisA ___ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/NEY4JKQMDTMS6PN3I6VK6FCICRLCG43P/ Code of Conduct: http://python.org/psf/codeofconduct/
[Python-ideas] Re: Addition to fnmatch.py
I think y’all have addressed the OP’s problem — at least the performance
issues.
But I think this brings up a pattern that I don’t have a nifty way to
address:
How do you divide a sequence into two sequences cleanly?
The filter pattern: selectively remove items from a sequence, returning a
new sequence. There are a few ways to do that in Python.
But what if you need both the remaining items and the removed ones? Easy
enough to write a loop that populates two lists, but is there a nifty
one-liner?
Is this a known functional pattern?
-CHB
On Sun, Jun 5, 2022 at 7:39 PM Eric V. Smith via Python-ideas <
python-ideas@python.org> wrote:
>
> On 6/5/2022 1:22 PM, Benedict Verhegghe wrote:
> > Op 5/06/2022 om 18:47 schreef David Mertz, Ph.D.:
> >> Sure, that's nice enough code and has the same big-O complexity. I
> >> suspect set difference is a little faster (by a constant multiple)
> >> because it hits C code more, but I haven't benchmarked.
> >>
> >> The OP said the elements were from fnmatch though, which explicitly
> >> does not promise order. So really it's just whether you like your
> >> code or this better aesthetically:
> >>
> >> list(set(b) - set(a))
> >>
> > I benchmarked it and indeed the list difference is a little faster.
> > >>> timeit.timeit('s=set(b); [x for x in a if x not in s]', setup='a =
> > list(range(1)); b = list(range(1000))', number=1000)
> > 0.6156670850032242
> > >>> timeit.timeit('list(set(a)-set(b))', setup='a =
> > list(range(1)); b = list(range(1000))', number=1000)
> > 0.43649216600169893
> >
> > And what's more, it seems to also preserve order. I guess because a
> > set is implemented like a dict, and will preserve order of you only
> > remove some elements from the set.
> >
> A set doesn't guarantee order at all, and indeed it does not preserve
> creation order:
>
> >>> s = set([10, 20, 1])
> >>> s
> {1, 10, 20}
>
> You're seeing an accidental byproduct of the implementation.
>
> Eric
>
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Christopher Barker, PhD (Chris)
Python Language Consulting
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