George Sakkis wrote:
>>Function name is perhaps not the best one. It occurs to me that this
>>is the GROUP BY in SQL so perhaps a different name is better, but
>>then again this might be moot if such a already exists somewhere :)
>
>
> Amazing, you keep reinventing things, even with the exact sam
> Function name is perhaps not the best one. It occurs to me that this
> is the GROUP BY in SQL so perhaps a different name is better, but
> then again this might be moot if such a already exists somewhere :)
Amazing, you keep reinventing things, even with the exact same name :)
from itertools im
Lasse Vågsæther Karlsen wrote:
>
>
> Another idea for this method would be that in some cases I noticed that
> it was useful to know which source each element would come from as well,
> as well as removing duplicates from the results.
>
The "removing duplicates" problem would probably be bes
Another idea for this method would be that in some cases I noticed that
it was useful to know which source each element would come from as well,
as well as removing duplicates from the results.
For instance
s1 = [1, 3, 5, 7]
s2 = [2, 3, 4]
for k, s in merge_by_sort(s1, s2):
print k, "fr
Mike C. Fletcher <[EMAIL PROTECTED]> wrote:
...
> One thing to keep in mind (if you care about performance) is that you
> one could use bisect, instead of sort, as the sorted list of streams is
> already in order save for the one element you are processing. Btw, nice
> trick with reverse to red
George Sakkis <[EMAIL PROTECTED]> wrote:
...
> > i.e., a heap solution may be over 4 times faster than a sort-based one
> > (in the following implementations).
>
> Interesting; I thought timsort on small almost ordered lists would be
> practically as fast as the heap. Still, how is 0.10344 over
Alex Martelli wrote:
>George Sakkis <[EMAIL PROTECTED]> wrote:
> ...
>
>
>>>manipulation of a heap to place an item in the right spot, but with 4-5
>>>or a few more sources might not make an impact at all.
>>>
>>>
>>Unless you're talking about hundreds or thousands sources, it probably
>
"Alex Martelli" <[EMAIL PROTECTED]> wrote:
> George Sakkis <[EMAIL PROTECTED]> wrote:
>...
> > > manipulation of a heap to place an item in the right spot, but with 4-5
> > > or a few more sources might not make an impact at all.
> >
> > Unless you're talking about hundreds or thousands source
George Sakkis <[EMAIL PROTECTED]> wrote:
...
> > manipulation of a heap to place an item in the right spot, but with 4-5
> > or a few more sources might not make an impact at all.
>
> Unless you're talking about hundreds or thousands sources, it probably
> won't. I would still go for the heap s
"Lasse Vågsæther Karlsen" <[EMAIL PROTECTED]> wrote:
> George Sakkis wrote:
>
> > Just added a recipe at
> > http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/440673. You can
try
> > both and see if there's any significant performance difference for your
> > data.
>
>
> Thanks, will take
George Sakkis wrote:
> Just added a recipe at
> http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/440673. You can try
> both and see if there's any significant performance difference for your data.
Thanks, will take a look at it later. The sort solution seems to work
nicely. Might be a b
"Lasse Vågsæther Karlsen" <[EMAIL PROTECTED]> wrote:
> Alex Martelli wrote:
> > George Sakkis <[EMAIL PROTECTED]> wrote:
>
> >>Yes, it's a little inconvenient that the builtin heap doesn't take a
> >>comparison operation but you can easily roll your own heap by transforming
> >>each item to a (ke
Alex Martelli wrote:
> George Sakkis <[EMAIL PROTECTED]> wrote:
>>Yes, it's a little inconvenient that the builtin heap doesn't take a
>>comparison operation but you can easily roll your own heap by transforming
>>each item to a (key,item) tuple. Now that I'm thinking about it, it might
>>be a goo
[Alex Martelli]
>>> try it (and read the Timbot's article included in Python's sources, and the
>>> sources themselves)...
[Kay Schluehr]
>> Just a reading advise. The translated PyPy source
>> pypy/objectspace/listsort.py might be more accessible than the
>> corresponding C code.
[cfbolz]
> inde
Kay Schluehr wrote:
> Alex Martelli wrote:
>
> > try it (and read the Timbot's article included in Python's sources, and the
> > sources themselves)...
>
> Just a reading advise. The translated PyPy source
> pypy/objectspace/listsort.py might be more accessible than the
> corresponding C code.
ind
Alex Martelli wrote:
> try it (and read the Timbot's article included in Python's sources, and the
> sources themselves)...
Just a reading advise. The translated PyPy source
pypy/objectspace/listsort.py might be more accessible than the
corresponding C code.
Kay
--
http://mail.python.org/mail
George Sakkis <[EMAIL PROTECTED]> wrote:
> "Lasse Vågsæther Karlsen" <[EMAIL PROTECTED]> wrote:
>
> > Thanks, that looks like Mike's solution except that it uses the
> > built-in heapq module.
>
> This make a big difference for the algorithmic complexity; replacing an
> item in a heap is much mo
Lasse Vågsæther Karlsen wrote:
> I need to merge several sources of values into one stream of values. All
> of the sources are sorted already and I need to retrieve the values from
Ok, after working through the various sources and solutions, here's what
I finally ended up with:
def merge_sort
Lasse Vågsæther Karlsen wrote:
>Ok, that one looks more sleak than what I came up with.
>
>Couple of things I learn from your solution, please correct me if I
>misunderstood something:
>
>1. list containing other lists will sort itself based on first element
>on lists inside ?
>
>
Correct, compa
"Lasse Vågsæther Karlsen" <[EMAIL PROTECTED]> wrote:
> Thanks, that looks like Mike's solution except that it uses the
> built-in heapq module.
This make a big difference for the algorithmic complexity; replacing an item in
a heap is much more
efficient than sorting the whole list.
> While this
Thanks, that looks like Mike's solution except that it uses the
built-in heapq module.
While this one contains less code than Mike's solution it seems to lack
the ability to control the comparison operation, which means it won't
work in my case. I need to both be able to sort on an arbitrary field
"Lasse Vågsæther Karlsen" <[EMAIL PROTECTED]> wrote:
> Ok, that one looks more sleak than what I came up with.
For the most efficient and elegant solution, check out Raymond Hettinger's
reply to:
http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/141934
George
--
http://mail.python.org
Ok, that one looks more sleak than what I came up with.
Couple of things I learn from your solution, please correct me if I
misunderstood something:
1. list containing other lists will sort itself based on first element
on lists inside ?
2. sort(), pop() is not costly operations
Other than that
Lasse Vågsæther Karlsen wrote:
>I need to merge several sources of values into one stream of values. All
>of the sources are sorted already and I need to retrieve the values from
>them all in sorted order.
>
>In other words:
>s1 = [10, 20, 30, 40, 50]
>s2 = [15, 25]
>s3 = [17, 27, 37]
>
>for val
Lasse Vågsæther Karlsen wrote:
> I need to merge several sources of values into one stream of values.
> All of the sources are sorted already and I need to retrieve the
> values from them all in sorted order.
>
> In other words:
> s1 = [10, 20, 30, 40, 50]
> s2 = [15, 25]
> s3 = [17, 27, 37]
>
>
I need to merge several sources of values into one stream of values. All
of the sources are sorted already and I need to retrieve the values from
them all in sorted order.
In other words:
s1 = [10, 20, 30, 40, 50]
s2 = [15, 25]
s3 = [17, 27, 37]
for value in ???(s1, s2, s3):
print value
w
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