Hi,
I posted this (by accident) off the list:
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:
100 -r 5 -v
mar...@v.loewis.de wrote:
It's faster than calling dict() because the dict code will
create a second dictionary, and discard the keywords dictionary.
Perhaps in the case where dict() is called with keyword
args only, it could just return the passed-in keyword
dictionary instead of creating
Greg Ewing, 15.11.2012 11:48:
mar...@v.loewis.de wrote:
It's faster than calling dict() because the dict code will
create a second dictionary, and discard the keywords dictionary.
Perhaps in the case where dict() is called with keyword
args only, it could just return the passed-in keyword
Stefan Behnel stefan_ml at behnel.de writes:
Right. If that makes a difference, it's another bug.
Stefan
It's fixed, with, I will note, fewer lines of code than many messages in this
thread:
https://bitbucket.org/pypy/pypy/changeset/c30cb1dcb7a9adc32548fd14274e4995
Alex
On 11/15/2012 9:58 AM, Stefan Behnel wrote:
Greg Ewing, 15.11.2012 11:48:
mar...@v.loewis.de wrote:
It's faster than calling dict() because the dict code will
create a second dictionary, and discard the keywords dictionary.
Perhaps in the case where dict() is called with keyword
args only,
On 15/11/2012 4:21pm, Terry Reedy wrote:
I was thinking that CPython could check the ref count of the input
keyword dict to determine whether it is newly created and can be
returned or is pre-existing and must be copied. But it seems not so.
def d(**x): return sys.getrefcount(x)
import sys
Stefan Behnel wrote:
This should work as long as this still creates a copy of d at some point:
d = {...}
dict(**d)
It will -- the implementation of the function call opcode always
creates a new keyword dict for passing to the called function.
--
Greg
On Nov 14, 2012, at 5:37 PM, Chris Withers wrote:
On 14/11/2012 10:11, mar...@v.loewis.de wrote:
Zitat von Chris Withers ch...@simplistix.co.uk:
a_dict = dict(
x = 1,
y = 2,
z = 3,
...
)
What can we do to speed up the former case?
It should be possible to
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
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
On 14/11/2012 09:58, Merlijn van Deen wrote:
On 14 November 2012 10:12, Chris Withers ch...@simplistix.co.uk 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 {}
Zitat von Chris Withers ch...@simplistix.co.uk:
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
Le Wed, 14 Nov 2012 10:00:59 +,
Chris Withers ch...@simplistix.co.uk a écrit :
On 14/11/2012 09:58, Merlijn van Deen wrote:
On 14 November 2012 10:12, Chris Withers ch...@simplistix.co.uk
wrote:
...which made me a little sad
Why did it make you sad? dict() takes 0.2µs, {} takes
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 ch...@simplistix.co.uk 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
On Wed, Nov 14, 2012 at 8:12 PM, Chris Withers ch...@simplistix.co.uk 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
2012/11/14 mar...@v.loewis.de:
Zitat von Chris Withers ch...@simplistix.co.uk:
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,
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,
'z':3,
...
}
What
On Wed, Nov 14, 2012 at 3:12 AM, Chris Withers ch...@simplistix.co.uk 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,
...
)
On Wed, Nov 14, 2012 at 10:12:54AM -0600, Mark Adam dreamingforw...@gmail.com
wrote:
On Wed, Nov 14, 2012 at 3:12 AM, Chris Withers ch...@simplistix.co.uk 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
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:
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
On Wed, Nov 14, 2012 at 10:12 AM, Mark Adam dreamingforw...@gmail.com wrote:
On Wed, Nov 14, 2012 at 3:12 AM, Chris Withers ch...@simplistix.co.uk 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:
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 section? I can't see such a
On Wed, Nov 14, 2012 at 11:02 AM, Xavier Morel python-...@masklinn.net 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 = {
'x': 1,
'y':
On Wed, Nov 14, 2012 at 11:00 AM, Brian Curtin br...@python.org wrote:
On Wed, Nov 14, 2012 at 10:12 AM, Mark Adam dreamingforw...@gmail.com wrote:
On Wed, Nov 14, 2012 at 3:12 AM, Chris Withers ch...@simplistix.co.uk
wrote:
Hi All,
A colleague pointed me at Doug's excellent article here:
On Wed, 14 Nov 2012 11:10:15 -0600, Mark Adam dreamingforw...@gmail.com wrote:
On Wed, Nov 14, 2012 at 11:00 AM, Brian Curtin br...@python.org wrote:
On Wed, Nov 14, 2012 at 10:12 AM, Mark Adam dreamingforw...@gmail.com
wrote:
On Wed, Nov 14, 2012 at 3:12 AM, Chris Withers
On Wed, Nov 14, 2012 at 11:27 AM, R. David Murray rdmur...@bitdance.com 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
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
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 a
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
**kwargs
On Wed, Nov 14, 2012 at 12:12 PM, Xavier Morel catch-...@masklinn.net 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
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
On Thu, Nov 15, 2012 at 12:18:38AM +1100, Chris Angelico ros...@gmail.com
wrote:
On Wed, Nov 14, 2012 at 8:12 PM, Chris Withers ch...@simplistix.co.uk wrote:
I suspect I'm not the only one who finds:
a_dict = dict(
x = 1,
y = 2,
z = 3,
...
)
...easier to
On Wed, Nov 14, 2012 at 1:37 PM, Xavier Morel catch-...@masklinn.net 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
On Wed, 14 Nov 2012 14:53:11 -0600
Mark Adam dreamingforw...@gmail.com wrote:
On Wed, Nov 14, 2012 at 1:37 PM, Xavier Morel catch-...@masklinn.net 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)
On 2012-11-14 20:53, Mark Adam wrote:
On Wed, Nov 14, 2012 at 1:37 PM, Xavier Morel catch-...@masklinn.net 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
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 catch-...@masklinn.net 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
On Wed, Nov 14, 2012 at 3:20 PM, MRAB pyt...@mrabarnett.plus.com wrote:
On 2012-11-14 20:53, Mark Adam wrote:
On Wed, Nov 14, 2012 at 1:37 PM, Xavier Morel catch-...@masklinn.net
wrote:
On 2012-11-14, at 19:54 , Mark Adam wrote:
Merging of two dicts is done with dict.update.
No,
MRAB wrote:
On 2012-11-14 20:53, Mark Adam wrote:
On Wed, Nov 14, 2012 at 1:37 PM, Xavier Morel catch-...@masklinn.net
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
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 valid identifier':
On Wed, Nov 14, 2012 at 3:40 PM, Brandon W Maister bwmais...@gmail.com 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:
On 2012-11-14, at 21:53 , Mark Adam wrote:
On Wed, Nov 14, 2012 at 1:37 PM, Xavier Morel catch-...@masklinn.net 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
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.
--
On 14/11/2012 10:11, mar...@v.loewis.de wrote:
Zitat von Chris Withers ch...@simplistix.co.uk:
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
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
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
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)
$ 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
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
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
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 st...@pearwood.info
On 15/11/12 05:54, Mark Adam
On Thu, Nov 15, 2012 at 10:36 AM, Steven D'Aprano st...@pearwood.info 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,
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
On Wed, Nov 14, 2012 at 5:40 PM, Chris Angelico ros...@gmail.com wrote:
On Thu, Nov 15, 2012 at 10:36 AM, Steven D'Aprano st...@pearwood.info 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
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
same as, or
On Thu, Nov 15, 2012 at 1:28 PM, Stephen J. Turnbull step...@xemacs.org 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?
On Wed, Nov 14, 2012 at 8:28 PM, Stephen J. Turnbull step...@xemacs.org 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?
Chris Angelico writes:
On Thu, Nov 15, 2012 at 1:28 PM, Stephen J. Turnbull step...@xemacs.org
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
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
appropriate
Zitat von Chris Withers ch...@simplistix.co.uk:
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 ;-)
Zitat von Chris Withers ch...@simplistix.co.uk:
$ 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)'
Zitat von Chris Angelico ros...@gmail.com:
On Thu, Nov 15, 2012 at 1:28 PM, Stephen J. Turnbull
step...@xemacs.org 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
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 loop
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,
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 -m timeit 'def
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
66 matches
Mail list logo
