Re: sum() vs. loop
On Mon, Oct 11, 2021 at 2:54 PM Steve Keller wrote: > I have found the sum() function to be much slower than to loop over the > operands myself: > > def sum_products(seq1, seq2): > return sum([a * b for a, b in zip(seq1, seq2)]) > > def sum_products2(seq1, seq2): > sum = 0 > for a, b in zip(seq1, seq2): > sum += a * b > return sum > > In a program I generate about 14 million pairs of sequences of ints each > of length 15 which need to be summed. The first version with sum() needs > 44 seconds while the second version runs in 37 seconds. > > Can someone explain this difference? > I can't explain it. It might help to try a line-by-line profiler. If you need speed, maybe try Cython, numpy and/or numba. It seems like the generator expression should be the fastest to me. But writing for speed instead of writing for clarity is usually not a great idea. -- https://mail.python.org/mailman/listinfo/python-list
Re: spyder does not work under root! [linux]
On 10/8/21 4:32 PM, Paulo da Silva wrote: > Às 22:56 de 08/10/21, Paulo da Silva escreveu: >> Hi! >> >> I need to debug a python3 script under root. I tried spyder but it does >> not work. >> >> Running as root without --no-sandbox is not supported. See >> https://crbug.com/638180. >> >> Thanks for any comments including alternative solutions to debug as root. >> > I also tried with eric and curiously it gave the same message!! > > This seems crazy. Not so crazy. It's incredibly dangerous to run a web browser as root. There's no reason I can think of for running a python script driving a web browser as root. Python scripts can easily be run as an arbitrary user, perhaps from a bash wrapper script using su, or being started from systemd. -- https://mail.python.org/mailman/listinfo/python-list
Re: Beginner problem, please help. Building a simple menu + lists , cannot print list
On Tue, Oct 12, 2021 at 9:13 AM Felix Kjellström wrote: > > Hello! Please see the link to the code I have uploaded to my account at > replit.com > > https://replit.com/join/lftxpszwrv-felixkjellstrom Unfortunately, it's not public. Are you able to put the code on GitHub as a repository or gist, or in some other public hosting? Alternatively, can you make it short enough to simply include here in your post? ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: Assign a value to a var content in an object
On Tue, Oct 12, 2021 at 9:03 AM Paulo da Silva wrote: > > Hello! > > Is there a better way of doing this? > Why didn't setattr (as commented) work? > > Thanks for an help/comments. > > class C: > def f(self,v): > #setattr(self,n,v) > self.__dict__['n']=v > > c=C() > c.f(3) > print(c.n) > Because setattr needs a string, just like the assignment to the dictionary does. Try: setattr(self, "n", v) Or, since it's a constant: self.n = v ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: sum() vs. loop
On Tue, Oct 12, 2021 at 9:02 AM Stefan Ram wrote: > > Steve Keller writes: > >Now completely surprised. > > I have observed that here the generator-based sum() call > is slower if both seq1 and seq2 have a length of 1000, but > faster if both seq1 and seq2 have 1000 entries each > (with float entries). > > However, in any case, the direct for-loop still is fastest. > Maybe, calling "next()" (actually, "PyIter_Next" in C) on > an iterator has some overhead compared to just evaluating > an expression in a loop. > There's overhead whichever way you do it, and ultimately, it depends on what you're doing. The genexp is effectively a callback into Python code. The list comp requires preconstruction of the entire list. The plain for loop involves summing by picking up and putting down in Python code rather than doing that in C. The only way to know which is fastest is to try them all :) ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Beginner problem, please help. Building a simple menu + lists , cannot print list
Hello! Please see the link to the code I have uploaded to my account at replit.com https://replit.com/join/lftxpszwrv-felixkjellstrom Problem: When you select the menu option "Add buyer", you can enter three values. See code line 5, "def Add_buyer ():" Then, you use the arrow keys to select the menu option "See list of buyers". When you do that the values you just entered should be printed. See code line 23, "def See_list_of_buyers (): The problem is that the list is DON'T gets printed. Problem: When you select the menu option "Add buyer", you can enter three values. See code line 5, "def Add_buyer ():" Then, you use the arrow keys to select the menu option "See list of buyers". When you do that the values you just entered should be printed. See code line 23, "def See_list_of_buyers (): The problem is that the list is DON'T gets printed. -- https://mail.python.org/mailman/listinfo/python-list
Re: sum() vs. loop
On Tue, Oct 12, 2021 at 8:55 AM Steve Keller wrote: > > I have found the sum() function to be much slower than to loop over the > operands myself: > > def sum_products(seq1, seq2): > return sum([a * b for a, b in zip(seq1, seq2)]) > > def sum_products2(seq1, seq2): > sum = 0 > for a, b in zip(seq1, seq2): > sum += a * b > return sum > > In a program I generate about 14 million pairs of sequences of ints each > of length 15 which need to be summed. The first version with sum() needs > 44 seconds while the second version runs in 37 seconds. > > Can someone explain this difference? > When you use sum, you're constructing a list. Try removing the square brackets: return sum(a * b for a, b in zip(seq1, seq2)) It's also possible that the genexp has more overhead than simply iterating directly, but at very least, this will reduce the memory consumption. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: Assign a value to a var content in an object
Às 23:28 de 10/10/21, Stefan Ram escreveu: > Paulo da Silva writes: >> class C: >>def f(self,v): >>#setattr(self,n,v) >>self.__dict__['n']=v > >> Why didn't setattr (as commented) work? > > Because the name n has not been initialized to a suitable > value in the function f. You could write > > setattr( self, "n", v ) Ah, OK - I missed the "" around n! :-( > > , but if you want this, > > self.n = v > > would be better. Of course :-) But that's not the purpose. This is just a toy example. Thanks. -- https://mail.python.org/mailman/listinfo/python-list
Re: spyder does not work under root! [linux]
On Tue, Oct 12, 2021 at 8:52 AM Paulo da Silva wrote: > > Hi! > > I need to debug a python3 script under root. I tried spyder but it does > not work. > > Running as root without --no-sandbox is not supported. See > https://crbug.com/638180. > > Thanks for any comments including alternative solutions to debug as root. > Did you try reading the linked bug report? Or running it with --no-sandbox? ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Assign a value to a var content in an object
Hello! Is there a better way of doing this? Why didn't setattr (as commented) work? Thanks for an help/comments. class C: def f(self,v): #setattr(self,n,v) self.__dict__['n']=v c=C() c.f(3) print(c.n) -- https://mail.python.org/mailman/listinfo/python-list
Re: sum() vs. loop
Christian Gollwitzer writes: > > def sum_products(seq1, seq2): > > return sum([a * b for a, b in zip(seq1, seq2)]) > > def sum_products2(seq1, seq2): > > sum = 0 > > for a, b in zip(seq1, seq2): > > sum += a * b > > return sum > > [...] > > The first version constructs a list, sums it up and throws the list > away, while the second version only keeps the running sum in > memory. How about a generator expression instead, i.e. > > > sum((a * b for a, b in zip(seq1, seq2))) Ah, of course. Much cleaner and I should have seen that myself. Thanks. BUT > (untested) ? I have tested it and with () instead of [] it's even slower: explicit loop: 37s ± .5s sum([...]) 44s ± .5s sum((...)) 47.5s ± .5s Now completely surprised. Steve -- https://mail.python.org/mailman/listinfo/python-list
Re: sum() vs. loop
Am 10.10.21 um 10:49 schrieb Steve Keller: I have found the sum() function to be much slower than to loop over the operands myself: def sum_products(seq1, seq2): return sum([a * b for a, b in zip(seq1, seq2)]) def sum_products2(seq1, seq2): sum = 0 for a, b in zip(seq1, seq2): sum += a * b return sum In a program I generate about 14 million pairs of sequences of ints each of length 15 which need to be summed. The first version with sum() needs 44 seconds while the second version runs in 37 seconds. The first version constructs a list, sums it up and throws the list away, while the second version only keeps the running sum in memory. How about a generator expression instead, i.e. sum((a * b for a, b in zip(seq1, seq2))) (untested) ? Christian -- https://mail.python.org/mailman/listinfo/python-list
Re: spyder does not work under root! [linux]
Às 22:56 de 08/10/21, Paulo da Silva escreveu: > Hi! > > I need to debug a python3 script under root. I tried spyder but it does > not work. > > Running as root without --no-sandbox is not supported. See > https://crbug.com/638180. > > Thanks for any comments including alternative solutions to debug as root. > I also tried with eric and curiously it gave the same message!! This seems crazy. -- https://mail.python.org/mailman/listinfo/python-list
sum() vs. loop
I have found the sum() function to be much slower than to loop over the operands myself: def sum_products(seq1, seq2): return sum([a * b for a, b in zip(seq1, seq2)]) def sum_products2(seq1, seq2): sum = 0 for a, b in zip(seq1, seq2): sum += a * b return sum In a program I generate about 14 million pairs of sequences of ints each of length 15 which need to be summed. The first version with sum() needs 44 seconds while the second version runs in 37 seconds. Can someone explain this difference? Steve -- https://mail.python.org/mailman/listinfo/python-list
spyder does not work under root! [linux]
Hi! I need to debug a python3 script under root. I tried spyder but it does not work. Running as root without --no-sandbox is not supported. See https://crbug.com/638180. Thanks for any comments including alternative solutions to debug as root. Paulo -- https://mail.python.org/mailman/listinfo/python-list
installazione numpy
l'installazione di numpy con pip install numpy fornisce errore Building wheel for numpy (PEP 517) ERROR: Failed building wheel for numpy Failed to build numpy ERROR: Could not build wheels for numpy which use PEP 517 and cannot be installed directly A cosa è dovuto e come devo fare per installare anche scipy che non riesce? Grazie -- https://mail.python.org/mailman/listinfo/python-list
Re: HELP - uninstall pyton error
give more details OS, Python Version, Method of installation.. etc.. On 10/7/21 17:18, Almadar Plus wrote: Could you please help me uninstall python? see attached screenshots files Regards -- https://mail.python.org/mailman/listinfo/python-list
nrfutil icorrect installation
Dear python,
I installed Python 3.10.0
I then install
pip install nrfutil
When I try to run nrfutil, I get
ModuleNotFoundError: No module named 'constants'
C:\Users\ x\nrfutil keys --help
Traceback (most recent call last):
File "C:\Users\Gerhard van
Rensburg\AppData\Local\Programs\Python\Python310\Scripts\nrfutil-script.py",
line 33, in
sys.exit(load_entry_point('nrfutil==5.2.0', 'console_scripts',
'nrfutil')())
File "C:\Users\Gerhard van
Rensburg\AppData\Local\Programs\Python\Python310\Scripts\nrfutil-script.py",
line 25, in importlib_load_entry_point
return next(matches).load()
File "C:\Users\Gerhard van
Rensburg\AppData\Local\Programs\Python\Python310\lib\importlib\metadata\__in
it__.py", line 162, in load
module = import_module(match.group('module'))
File "C:\Users\Gerhard van
Rensburg\AppData\Local\Programs\Python\Python310\lib\importlib\__init__.py",
line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "", line 1050, in _gcd_import
File "", line 1027, in _find_and_load
File "", line 1006, in
_find_and_load_unlocked
File "", line 688, in _load_unlocked
File "", line 883, in exec_module
File "", line 241, in
_call_with_frames_removed
File "C:\Users\Gerhard van
Rensburg\AppData\Local\Programs\Python\Python310\lib\site-packages\nordicsem
i\__main__.py", line 53, in
from nordicsemi.dfu.dfu_transport_serial import DfuTransportSerial
File "C:\Users\Gerhard van
Rensburg\AppData\Local\Programs\Python\Python310\lib\site-packages\nordicsem
i\dfu\dfu_transport_serial.py", line 52, in
from nordicsemi.lister.device_lister import DeviceLister
File "C:\Users\Gerhard van
Rensburg\AppData\Local\Programs\Python\Python310\lib\site-packages\nordicsem
i\lister\device_lister.py", line 39, in
from nordicsemi.lister.windows.lister_win32 import Win32Lister
File "C:\Users\Gerhard van
Rensburg\AppData\Local\Programs\Python\Python310\lib\site-packages\nordicsem
i\lister\windows\lister_win32.py", line 43, in
from constants import DIGCF_PRESENT, DEVPKEY, DIGCF_DEVICEINTERFACE
ModuleNotFoundError: No module named 'constants'
Any help appreciated
Gerhard van Rensburg
___
RENIX
Electronics, Inc.
*713-503-0855 * Fax: 281-517-0773
* i...@renix-electronics.com
_
**All communications should be considered RENIX Confidential**
--
https://mail.python.org/mailman/listinfo/python-list
