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How can I multiply and divide using only bit shifting and adding?
...kes a constant multiple of time compared to addition and shifting. If I recall correctly, modern processors, if pipelined properly, can do multiplication just about as fast as addition, by messing with the utilization of the ALUs (arithmetic units) in the processor.
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What are metaclasses in Python?
...ass is an instance of a metaclass.
While in Python you can use arbitrary callables for metaclasses (like Jerub shows), the better approach is to make it an actual class itself. type is the usual metaclass in Python. type is itself a class, and it is its own type. You won't be able to recreate somet...
How to use the 'sweep' function
...; df_T
[,1] [,2] [,3] [,4] [,5]
[1,] 56.15561 39.03218 57.46965 49.22319 40.28305
[2,] 50.42946 40.15594 41.31905 60.87539 42.56695
[3,] 37.30704 54.98946 47.12317 39.44109 63.12203
[4,] 43.51037 53.86571 40.81435 59.43685 57.93136
[5,] 62.59752 61.95672 63.27377 41.02349 46...
How to make an unaware datetime timezone aware in python
...ize(unaware)
assert aware == now_aware
For the UTC timezone, it is not really necessary to use localize since there is no daylight savings time calculation to handle:
now_aware = unaware.replace(tzinfo=pytz.UTC)
works. (.replace returns a new datetime; it does not modify unaware.)
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Access an arbitrary element in a dictionary in Python
...
for a non-destructive popitem you can make a (shallow) copy: key, value = dict(d).popitem()
– Pelle
Jan 31 '18 at 10:35
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Why do x86-64 systems have only a 48 bit virtual address space?
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Because that's all that's needed. 48 bits give you an address space of 256 terabyte. That's a lot. You're not going to see a system which needs more than that any time soon.
So CPU manufacturers took a shortcut. They use an instruction set...
Calling generic method with a type argument known only at execution time [duplicate]
...t notation - there's no point in using a query expression when you've basically just got a where clause.
using System;
using System.Linq;
using System.Reflection;
namespace Interfaces
{
interface IFoo {}
interface IBar {}
interface IBaz {}
}
public class Test
{
public static void ...
php Replacing multiple spaces with a single space [duplicate]
...e: preg_replace('/(?:\s\s+|\n|\t)/', ' ', $x) will be more efficient especially on text with several single spaces ?
– codaddict
Mar 3 '10 at 4:23
27
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Converting string to numeric [duplicate]
... added a timing in a new answer. +1 for you as you had it correct and gave all options.
– Joris Meys
Feb 8 '11 at 10:23
1
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How to save a list as numpy array in python?
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First of all, I'd recommend you to go through NumPy's Quickstart tutorial, which will probably help with these basic questions.
You can directly create an array from a list as:
import numpy as np
a = np.array( [2,3,4] )
Or from a fr...