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How to combine two or more querysets in a Django view?
...t_list),
key=lambda instance: instance.date_created)
If you're using Python 2.4 or later, you can use attrgetter instead of a lambda. I remember reading about it being faster, but I didn't see a noticeable speed difference for a million item list.
from operator import attrgetter
result_list =...
Is there an interpreter for C? [closed]
...ng like an interpreter for C. That is, in a Linux terminal I can type in "python" and then code in that interpreter. (I'm not sure interpreter the right word). This is really helpful for testing different things out and I'm curious if something similar exists for C. Though I doubt it. The only ...
Automatically remove Subversion unversioned files
...on to do this:
svn cleanup --remove-unversioned
Before that, I use this python script to do that:
import os
import re
def removeall(path):
if not os.path.isdir(path):
os.remove(path)
return
files=os.listdir(path)
for x in files:
fullpath=os.path.join(path, x)...
Most lightweight way to create a random string and a random hexadecimal number
...
Interesting, I kind of forgot that Python (and the random module) handles bigints natively.
– wump
May 6 '10 at 18:49
3
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Why Collections.sort uses merge sort instead of quicksort?
...was a fine choice, but today but we can
do much better.
Since 2003, Python's list sort has used an algorithm known as timsort
(after Tim Peters, who wrote it). It is a stable, adaptive, iterative
mergesort that requires far fewer than n log(n) comparisons when
running on partially sorte...
How to convert a boolean array to an int array
...d seeing all the different ways to do it. Really opened my mind regarding python.
– Kwolf
Jul 6 '13 at 20:49
...
Keep only date part when using pandas.to_datetime
...osed, it does not really solve the performance problem (it still relies on python datetime objects, and hence any operation on them will be not vectorized - that is, it will be slow).
A better performing alternative is to use df['dates'].dt.floor('d'). Strictly speaking, it does not "keep only date...
Bitwise operation and usage
...10 0101
1111 1111 << 4 gives 1111 0000
Note that the left shift in Python is unusual in that it's not using a fixed width where bits are discarded - while many languages use a fixed width based on the data type, Python simply expands the width to cater for extra bits. In order to get the dis...
写出高质量代码的10个Tips - 更多技术 - 清泛网 - 专注C/C++及内核技术
...出更加地道的代码，充分发挥各自平台的优势。
基础的数据结构与算法，掌握好这些在解决一些特定问题时，可以以更加优雅有效的方式处理。
基础的设计原则，无需完全掌握23种经典设计模式，只需要了解一些常用的设计原...
C++ stl stack/queue 的使用方法 - C/C++ - 清泛网 - 专注C/C++及内核技术
...，最困难的可能就是如何定义比较算子了。
如果是基本数据类型，或已定义了比较运算符的类，可以直接用STL 的less 算子和greater算子——默认为使用less 算子，即小的往前排，大的先出队。
如果要定义自己的比较算子，方法...