Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Serhiy Storchaka
On 15.11.12 01:47, Terry Reedy wrote: 4. There are about 3000 issues on the tracker. Nearly all are worth more attention than this ;-). This is the best conclusion of this thread. ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.o

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Stefan Behnel
Chris Withers, 15.11.2012 08:14: > On 15/11/2012 06:32, Stefan Behnel wrote: >> Donald Stufft, 15.11.2012 00:00: >>> $ pypy -m timeit 'dict()' >>> 10 loops, best of 3: 0.000811 usec per loop >>> >>> $ pypy -m timeit '{}' >>> 10 loops, best of 3: 0.000809 usec per loop >>> >>> $ pypy

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Chris Withers
On 15/11/2012 06:32, Stefan Behnel wrote: Donald Stufft, 15.11.2012 00:00: $ pypy -m timeit 'dict()' 10 loops, best of 3: 0.000811 usec per loop $ pypy -m timeit '{}' 10 loops, best of 3: 0.000809 usec per loop $ pypy -m timeit 'def md(**kw): return kw; md()' 1 loops, b

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Stefan Behnel
Donald Stufft, 15.11.2012 00:00: > $ pypy -m timeit 'dict()' > 10 loops, best of 3: 0.000811 usec per loop > > $ pypy -m timeit '{}' > 10 loops, best of 3: 0.000809 usec per loop > > $ pypy -m timeit 'def md(**kw): return kw; md()' > 1 loops, best of 3: 0.0182 usec per

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread martin
Zitat von Chris Angelico : On Thu, Nov 15, 2012 at 1:28 PM, Stephen J. Turnbull wrote: Chris Angelico writes: > >>> {"a":1}+{"b":2} > It would make sense for this to result in {"a":1,"b":2}. The test is not "does this sometimes make sense?" It's "does this ever result in nonsense, and

Re: [Python-Dev] performance of {} versus dict(), de fmd(**kw): return kw trumps all ; -)

2012-11-14 Thread martin
Zitat von Chris Withers : $ python2.7 -m timeit -n 100 -r 5 -v "{'a':1,'b':2,'c':3,'d':4,'e':5,'f':6,'g':7}" raw times: 1.49 1.49 1.5 1.49 1.48 100 loops, best of 5: 1.48 usec per loop $ python2.7 -m timeit -n 100 -r 5 -v 'dict(a=1,b=2,c=3,d=4,e=5,f=6,g=7)' raw times: 2.35 2.36 2

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread martin
Zitat von Chris Withers : On 14/11/2012 21:40, Greg Ewing wrote: * If the compiler were allowed to recognise builtins, it could turn dict(a = 1, b = 2) into {'a':1, 'b':2} automatically. That would be my naive suggestion, I am prepared to be shot down in flames ;-) In general, special-ca

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Stephen J. Turnbull
Mark Adam writes: > Easy: dict should have a (user substitutable) collision function that > is called in these cases. "I smell overengineering." > This would allow significant functionality with practically no > cost. We already have that functionality if we want it; just define an appropr

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Stephen J. Turnbull
Chris Angelico writes: > On Thu, Nov 15, 2012 at 1:28 PM, Stephen J. Turnbull > wrote: > > Chris Angelico writes: > > > > > >>> {"a":1}+{"b":2} > > > > > It would make sense for this to result in {"a":1,"b":2}. > > > > The test is not "does this sometimes make sense?" It's "does this

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Mark Adam
On Wed, Nov 14, 2012 at 8:28 PM, Stephen J. Turnbull wrote: > Chris Angelico writes: > > > >>> {"a":1}+{"b":2} > > > It would make sense for this to result in {"a":1,"b":2}. > > The test is not "does this sometimes make sense?" It's "does this > ever result in nonsense, and if so, do we care?"

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Chris Angelico
On Thu, Nov 15, 2012 at 1:28 PM, Stephen J. Turnbull wrote: > Chris Angelico writes: > > > >>> {"a":1}+{"b":2} > > > It would make sense for this to result in {"a":1,"b":2}. > > The test is not "does this sometimes make sense?" It's "does this > ever result in nonsense, and if so, do we care?"

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Stephen J. Turnbull
Chris Angelico writes: > >>> {"a":1}+{"b":2} > It would make sense for this to result in {"a":1,"b":2}. The test is not "does this sometimes make sense?" It's "does this ever result in nonsense, and if so, do we care?" Here, addition is usually commutative. Should {'a':1}+{'a':2} be the sam

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Mark Adam
On Wed, Nov 14, 2012 at 5:40 PM, Chris Angelico wrote: > On Thu, Nov 15, 2012 at 10:36 AM, Steven D'Aprano wrote: >> On 15/11/12 05:54, Mark Adam wrote: >> Notice that I'm not merging one dict into another, but merging two dicts >> into a third. > > Side point: Wouldn't it be quite logical to sup

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Terry Reedy
On 11/14/2012 4:12 AM, Chris Withers wrote: To somewhat paraphrase: ''' I prefer 'dict(a=1,b=2,c=3,d=4,e=5,f=6,g=7)' to "{'a':1,'b':2,'c':3,'d':4,'e':5,'f':6,'g':7}". I am sad that the former takes +-2 times as long to run (in 2.7). Is the difference about the same in 3.x? What can we do to speed

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Chris Angelico
On Thu, Nov 15, 2012 at 10:36 AM, Steven D'Aprano wrote: > On 15/11/12 05:54, Mark Adam wrote: > >> Merging of two dicts is done with dict.update. How do you do it on >> initialization? This doesn't make sense. > > > Frequently. > > my_prefs = dict(default_prefs, setting=True, another_setting=F

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Lukas Lueg
Notice that {'x':1} and dict(x=1) are different beasts: The first one compiles directly to BUILD_MAP. The second one loads a reference to 'dict' from globals() and calls the constructor. The two are not the same. 2012/11/15 Steven D'Aprano > On 15/11/12 05:54, Mark Adam wrote: > > Merging of

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Steven D'Aprano
On 15/11/12 05:54, Mark Adam wrote: Merging of two dicts is done with dict.update. How do you do it on initialization? This doesn't make sense. Frequently. my_prefs = dict(default_prefs, setting=True, another_setting=False) Notice that I'm not merging one dict into another, but merging t

Re: [Python-Dev] performance of {} versus dict(), de fmd(**kw): return kw trumps all ; -)

2012-11-14 Thread Xavier Morel
On 2012-11-14, at 23:43 , Chris Withers wrote: > On 14/11/2012 22:37, Chris Withers wrote: >> On 14/11/2012 10:11, mar...@v.loewis.de wrote: >>> def xdict(**kwds): >>> return kwds >> >> Hah, good call, this trumps both of the other options: >> >> $ python2.7 -m timeit -n 100 -r 5 -v >> "{

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Donald Stufft
$ pypy -m timeit 'dict()' 10 loops, best of 3: 0.000811 usec per loop $ pypy -m timeit '{}' 10 loops, best of 3: 0.000809 usec per loop $ pypy -m timeit 'def md(**kw): return kw; md()' 1 loops, best of 3: 0.0182 usec per loop $ pypy -m timeit -s 'def md(**kw): return

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread MRAB
On 2012-11-14 21:40, Greg Ewing wrote: Chris Angelico wrote: Perhaps an alternative question: What can be done to make the latter less unpalatable? * We could introduce a new syntax such as {a = 1, b = 2}. * If the compiler were allowed to recognise builtins, it could turn dict(a = 1, b = 2)

Re: [Python-Dev] performance of {} versus dict(), de fmd(**kw): return kw trumps all ; -)

2012-11-14 Thread Chris Withers
On 14/11/2012 22:37, Chris Withers wrote: On 14/11/2012 10:11, mar...@v.loewis.de wrote: def xdict(**kwds): return kwds Hah, good call, this trumps both of the other options: $ python2.7 -m timeit -n 100 -r 5 -v "{'a':1,'b':2,'c':3,'d':4,'e':5,'f':6,'g':7}" raw times: 1.45 1.45 1.44 1.

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Chris Withers
On 14/11/2012 21:40, Greg Ewing wrote: * If the compiler were allowed to recognise builtins, it could turn dict(a = 1, b = 2) into {'a':1, 'b':2} automatically. That would be my naive suggestion, I am prepared to be shot down in flames ;-) Would be even more awesome if it could end up with t

Re: [Python-Dev] performance of {} versus dict(), de fmd(**kw): return kw trumps all ; -)

2012-11-14 Thread Chris Withers
On 14/11/2012 10:11, mar...@v.loewis.de wrote: Zitat von Chris Withers : a_dict = dict( x = 1, y = 2, z = 3, ... ) What can we do to speed up the former case? It should be possible to special-case it. Rather than creating a new dictionary from scratch, one could try to

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Greg Ewing
Chris Angelico wrote: Perhaps an alternative question: What can be done to make the latter less unpalatable? * We could introduce a new syntax such as {a = 1, b = 2}. * If the compiler were allowed to recognise builtins, it could turn dict(a = 1, b = 2) into {'a':1, 'b':2} automatically. -- G

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Xavier Morel
On 2012-11-14, at 21:53 , Mark Adam wrote: > On Wed, Nov 14, 2012 at 1:37 PM, Xavier Morel wrote: >> On 2012-11-14, at 19:54 , Mark Adam wrote: >>> >>> Merging of two dicts is done with dict.update. >> >> No, dict.update merges one dict (or two) into a third one. > > No. I think you need to r

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Brian Curtin
On Wed, Nov 14, 2012 at 3:40 PM, Brandon W Maister wrote: > >> >> To (mis-)quote Antoine: >> >--> d1 = {1:2} >> >--> d2 = {'3':4} >> >--> dict(d1, **d2) >> > {1: 2, '3': 4} >> >> Apparently it is valid syntax. Just make sure you keys for the ** >> operator are valid strings. :) >> > > or not: >

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Brandon W Maister
> > To (mis-)quote Antoine: > >--> d1 = {1:2} > >--> d2 = {'3':4} > >--> dict(d1, **d2) > > {1: 2, '3': 4} > > Apparently it is valid syntax. Just make sure you keys for the ** > operator are valid strings. :) > > or not: >>> dict(**{'not a valid identifier': True, 1: True}) {1: True, 'not a val

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Ethan Furman
MRAB wrote: On 2012-11-14 20:53, Mark Adam wrote: On Wed, Nov 14, 2012 at 1:37 PM, Xavier Morel wrote: On 2012-11-14, at 19:54 , Mark Adam wrote: Merging of two dicts is done with dict.update. No, dict.update merges one dict (or two) into a third one. No. I think you need to read the do

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Brian Curtin
On Wed, Nov 14, 2012 at 3:20 PM, MRAB wrote: > On 2012-11-14 20:53, Mark Adam wrote: >> >> On Wed, Nov 14, 2012 at 1:37 PM, Xavier Morel >> wrote: >>> >>> On 2012-11-14, at 19:54 , Mark Adam wrote: Merging of two dicts is done with dict.update. >>> >>> >>> No, dict.update merges on

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread MRAB
On 2012-11-14 21:20, MRAB wrote: On 2012-11-14 20:53, Mark Adam wrote: On Wed, Nov 14, 2012 at 1:37 PM, Xavier Morel wrote: On 2012-11-14, at 19:54 , Mark Adam wrote: Merging of two dicts is done with dict.update. No, dict.update merges one dict (or two) into a third one. No. I think yo

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread MRAB
On 2012-11-14 20:53, Mark Adam wrote: On Wed, Nov 14, 2012 at 1:37 PM, Xavier Morel wrote: On 2012-11-14, at 19:54 , Mark Adam wrote: Merging of two dicts is done with dict.update. No, dict.update merges one dict (or two) into a third one. No. I think you need to read the docs. How do

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Antoine Pitrou
On Wed, 14 Nov 2012 14:53:11 -0600 Mark Adam wrote: > On Wed, Nov 14, 2012 at 1:37 PM, Xavier Morel wrote: > > On 2012-11-14, at 19:54 , Mark Adam wrote: > >> > >> Merging of two dicts is done with dict.update. > > > > No, dict.update merges one dict (or two) into a third one. > > No. I think y

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Mark Adam
On Wed, Nov 14, 2012 at 1:37 PM, Xavier Morel wrote: > On 2012-11-14, at 19:54 , Mark Adam wrote: >> >> Merging of two dicts is done with dict.update. > > No, dict.update merges one dict (or two) into a third one. No. I think you need to read the docs. >> How do you do it on >> initialization?

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Oleg Broytman
On Thu, Nov 15, 2012 at 12:18:38AM +1100, Chris Angelico wrote: > On Wed, Nov 14, 2012 at 8:12 PM, Chris Withers wrote: > > I suspect I'm not the only one who finds: > > > > a_dict = dict( > > x = 1, > > y = 2, > > z = 3, > > ... > > ) > > > > ...easier to read than: > > > >

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Xavier Morel
On 2012-11-14, at 19:54 , Mark Adam wrote: > > Merging of two dicts is done with dict.update. No, dict.update merges one dict (or two) into a third one. > How do you do it on > initialization? This doesn't make sense. dict(d1, **d2) ___ Python-Dev ma

Re: [Python-Dev] [Distutils] [Catalog-sig] accept the wheel PEPs425, 426, 427

2012-11-14 Thread a.cavallo
Mmmm, interesting point and worth a discussion about different roles (developer, system admin, final user etc.) having different needs. I believe distutils is used as tool primarily (setup.py bdist_rpm/msi to create installable objects, setup.py bdist_sdist to manage the source code etc.): this

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Mark Adam
On Wed, Nov 14, 2012 at 12:12 PM, Xavier Morel wrote: > On 2012-11-14, at 18:10 , Mark Adam wrote: >> >> Try the canonical {'x':1}. Only dict allows the special >> initialization above. Other collections require an iterable. > > Other collections don't have a choice, because it would often be >

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Xavier Morel
On 2012-11-14, at 18:10 , Mark Adam wrote: > > Try the canonical {'x':1}. Only dict allows the special > initialization above. Other collections require an iterable. Other collections don't have a choice, because it would often be ambiguous. Dicts do not have that issue. > I'm guessing > **kw

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Xavier Morel
On 2012-11-14, at 18:08 , Mark Adam wrote: > > That's not a recommendation to use the **kwargs style. And nobody said it was. It's a recommendation to not put spaces around the equals sign when using keyword arguments which is the correction Serhiy applied to the original code (along with adding

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Richard Oudkerk
On 14/11/2012 5:02pm, Xavier Morel wrote: In which section? I can't see such a recommendation. Whitespace in Expressions and Statements > Other Recommendations 3rd bullet: — Don't use spaces around the = sign when used to indicate a keyword argument or a default parameter value. Oops, I d

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Mark Adam
On Wed, Nov 14, 2012 at 11:27 AM, R. David Murray wrote: > Maybe it's not good design, but I'll bet you that if it didn't do that, > there would be lots of instances of this scattered around various > codebases: > > def makedict(**kw): > return kw Now that's a good solution and probab

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread R. David Murray
On Wed, 14 Nov 2012 11:10:15 -0600, Mark Adam wrote: > On Wed, Nov 14, 2012 at 11:00 AM, Brian Curtin wrote: > > On Wed, Nov 14, 2012 at 10:12 AM, Mark Adam > > wrote: > >> On Wed, Nov 14, 2012 at 3:12 AM, Chris Withers > >> wrote: > >>> Hi All, > >>> > >>> A colleague pointed me at Doug's ex

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Mark Adam
On Wed, Nov 14, 2012 at 11:00 AM, Brian Curtin wrote: > On Wed, Nov 14, 2012 at 10:12 AM, Mark Adam wrote: >> On Wed, Nov 14, 2012 at 3:12 AM, Chris Withers >> wrote: >>> Hi All, >>> >>> A colleague pointed me at Doug's excellent article here: >>> ...which made me a little sad, I suspect I'm no

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Mark Adam
On Wed, Nov 14, 2012 at 11:02 AM, Xavier Morel wrote: > > On 2012-11-14, at 17:42 , Richard Oudkerk wrote: > >> On 14/11/2012 4:23pm, Serhiy Storchaka wrote: >>> PEP 8 recommends: >>> >>> a_dict = dict( >>> x=1, >>> y=2, >>> z=3, >>> ... >>> ) >>> >>> and >>> >>> a_dict = { >>>

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Xavier Morel
On 2012-11-14, at 17:42 , Richard Oudkerk wrote: > On 14/11/2012 4:23pm, Serhiy Storchaka wrote: >> PEP 8 recommends: >> >> a_dict = dict( >> x=1, >> y=2, >> z=3, >> ... >> ) >> >> and >> >> a_dict = { >> 'x': 1, >> 'y': 2, >> 'z': 3, >> ... >> } > > In which s

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Brian Curtin
On Wed, Nov 14, 2012 at 10:12 AM, Mark Adam wrote: > On Wed, Nov 14, 2012 at 3:12 AM, Chris Withers wrote: >> Hi All, >> >> A colleague pointed me at Doug's excellent article here: >> ...which made me a little sad, I suspect I'm not the only one who finds: >> >> a_dict = dict( >> x = 1, >>

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Richard Oudkerk
On 14/11/2012 4:23pm, Serhiy Storchaka wrote: PEP 8 recommends: a_dict = dict( x=1, y=2, z=3, ... ) and a_dict = { 'x': 1, 'y': 2, 'z': 3, ... } In which section? I can't see such a recommendation. -- Richard

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Serhiy Storchaka
On 14.11.12 11:12, Chris Withers wrote: which made me a little sad, I suspect I'm not the only one who finds: a_dict = dict( x = 1, y = 2, z = 3, ... ) easier to read than: a_dict = { 'x':1, 'y':2, 'z':3, ... } PEP 8 recommends: a_di

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Oleg Broytman
On Wed, Nov 14, 2012 at 10:12:54AM -0600, Mark Adam wrote: > On Wed, Nov 14, 2012 at 3:12 AM, Chris Withers wrote: > > Hi All, > > > > A colleague pointed me at Doug's excellent article here: > > ...which made me a little sad, I suspect I'm not the only one who finds: > > > > a_dict = dict( > >

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Mark Adam
On Wed, Nov 14, 2012 at 3:12 AM, Chris Withers wrote: > Hi All, > > A colleague pointed me at Doug's excellent article here: > ...which made me a little sad, I suspect I'm not the only one who finds: > > a_dict = dict( > x = 1, > y = 2, > z = 3, > ... > ) > > ...easier to read

Re: [Python-Dev] [Distutils] [Catalog-sig] accept the wheel PEPs 425, 426, 427

2012-11-14 Thread Daniel Holth
Well, you can build eggs with Bento, and I have a patch that allows it to build wheels, in both cases it will produce pip-compatible metadata. The Bento author has his own informed opinions about the way packaging should work which do not necessarily include the packaging PEPs. ___

Re: [Python-Dev] [Distutils] [Catalog-sig] accept the wheel PEPs 425, 426, 427

2012-11-14 Thread Paul Moore
On 14 November 2012 12:04, Daniel Holth wrote: > That has been tried already (setuptools, distribute, distutils2). Instead, > try bento (http://cournape.github.com/Bento/). > > Hilariously everyone I've showed it to is immediately put off by the > indentation based syntax (who would use such a th

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Stefan Behnel
Chris Angelico, 14.11.2012 14:18: > On Wed, Nov 14, 2012 at 8:12 PM, Chris Withers wrote: >> I suspect I'm not the only one who finds: >> >> a_dict = dict( >> x = 1, >> y = 2, >> z = 3, >> ... >> ) >> >> ...easier to read than: >> >> a_dict = { >> 'x':1, >> 'y':2, >>

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Benjamin Peterson
2012/11/14 : > > Zitat von Chris Withers : > > >> a_dict = dict( >> x = 1, >> y = 2, >> z = 3, >> ... >> ) > > >> What can we do to speed up the former case? > > > It should be possible to special-case it. Rather than creating > a new dictionary from scratch, one could try to h

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Chris Angelico
On Wed, Nov 14, 2012 at 8:12 PM, Chris Withers wrote: > I suspect I'm not the only one who finds: > > a_dict = dict( > x = 1, > y = 2, > z = 3, > ... > ) > > ...easier to read than: > > a_dict = { > 'x':1, > 'y':2, > 'z':3, > ... > } > > What can we do to sp

Re: [Python-Dev] [Distutils] [Catalog-sig] accept the wheel PEPs 425, 426, 427

2012-11-14 Thread Daniel Holth
On Nov 14, 2012, at 2:23 AM, Ronald Oussoren wrote: > > On 13 Nov, 2012, at 17:21, Antoine Pitrou wrote: > >> Le Tue, 13 Nov 2012 16:10:30 +0100, >> Ronald Oussoren a écrit : >>> >>> On 13 Nov, 2012, at 16:00, Daniel Holth wrote: I want to remove distutils from the standard libra

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Steven D'Aprano
On 14/11/12 21:00, Chris Withers wrote: On 14/11/2012 09:58, Merlijn van Deen wrote: On 14 November 2012 10:12, Chris Withers wrote: ...which made me a little sad Why did it make you sad? dict() takes 0.2µs, {} takes 0.04µs. In other words: you can run dict() _five million_ times per second,

Re: [Python-Dev] Python-Dev Digest, Vol 112, Issue 23

2012-11-14 Thread Peter Harris
Chris Withers wrote: > On 14/11/2012 09:58, Merlijn van Deen wrote: > > On 14 November 2012 10:12, Chris Withers wrote: > >> ...which made me a little sad > > > > Why did it make you sad? dict() takes 0.2?s, {} takes 0.04?s. In other > > words: you can run dict() _five million_ times per second,

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Antoine Pitrou
Le Wed, 14 Nov 2012 10:00:59 +, Chris Withers a écrit : > On 14/11/2012 09:58, Merlijn van Deen wrote: > > On 14 November 2012 10:12, Chris Withers > > wrote: > >> ...which made me a little sad > > > > Why did it make you sad? dict() takes 0.2µs, {} takes 0.04µs. In > > other words: you can r

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread martin
Zitat von Chris Withers : a_dict = dict( x = 1, y = 2, z = 3, ... ) What can we do to speed up the former case? It should be possible to special-case it. Rather than creating a new dictionary from scratch, one could try to have the new dictionary the same size as the or

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Chris Withers
On 14/11/2012 09:58, Merlijn van Deen wrote: On 14 November 2012 10:12, Chris Withers wrote: ...which made me a little sad Why did it make you sad? dict() takes 0.2µs, {} takes 0.04µs. In other words: you can run dict() _five million_ times per second, and {} twenty-five million times per sec

Re: [Python-Dev] performance of {} versus dict()

2012-11-14 Thread Ulrich Eckhardt
Am 14.11.2012 10:12, schrieb Chris Withers: Can someone with Python 3 handy compare there too? C:\Python27\python -m timeit -n 100 -r 5 -v "dict(a=1, b=2, c=3, d=4, e=5, f=6, g=7)" raw times: 0.918 0.924 0.922 0.928 0.926 100 loops, best of 5: 0.918 usec per loop C:\Python27\python

[Python-Dev] performance of {} versus dict()

2012-11-14 Thread Chris Withers
Hi All, A colleague pointed me at Doug's excellent article here: http://www.doughellmann.com/articles/misc/dict-performance/index.html ...which made me a little sad, I suspect I'm not the only one who finds: a_dict = dict( x = 1, y = 2, z = 3, ... ) ...easier to read than: