I was just re-reading What’s New In Python 3.0 and it states: The round() function rounding strategy and return type have changed. Exact halfway cases are now rounded to the nearest even result instead of away from zero. (For example, round(2.5) now returns 2 rather than 3.) and the documentation for round: For the built-in … Read more
How do you access other class variables from a list comprehension within the class definition? The following works in Python 2 but fails in Python 3: class Foo: x = 5 y = [x for i in range(1)] Python 3.2 gives the error: NameError: global name ‘x’ is not defined Trying Foo.x doesn’t work either. … Read more
How do I strip all the spaces in a python string? For example, I want a string like strip my spaces to be turned into stripmyspaces, but I cannot seem to accomplish that with strip(): >>> ‘strip my spaces’.strip() ‘strip my spaces’ 12 Answers 12
Although I have never needed this, it just struck me that making an immutable object in Python could be slightly tricky. You can’t just override __setattr__, because then you can’t even set attributes in the __init__. Subclassing a tuple is a trick that works: class Immutable(tuple): def __new__(cls, a, b): return tuple.__new__(cls, (a, b)) @property … Read more
In Python, is there a way to ping a server through ICMP and return TRUE if the server responds, or FALSE if there is no response? 32 Answers 32 If you don’t need to support Windows, here’s a really concise way to do it: import os hostname = “google.com” #example response = os.system(“ping -c 1 … Read more
I had two versions of Python installed on my machine (versions 2.6 and 2.5). I want to run 2.6 for one project and 2.5 for another. How can I specify which I want to use? I am working on Windows XP SP2. 20 Answers 20
What does the / mean in Python 3.4’s help output for range before the closing parenthesis? >>> help(range) Help on class range in module builtins: class range(object) | range(stop) -> range object | range(start, stop[, step]) -> range object | | Return a virtual sequence of numbers from start to stop by step. | | … Read more
I have this program that calculates the time taken to answer a specific question, and quits out of the while loop when answer is incorrect, but i want to delete the last calculation, so i can call min() and it not be the wrong time, sorry if this is confusing. from time import time q … Read more
I found that in Python 3.4 there are few different libraries for multiprocessing/threading: multiprocessing vs threading vs asyncio. But I don’t know which one to use or is the “recommended one”. Do they do the same thing, or are different? If so, which one is used for what? I want to write a program that … Read more
Using Python 3’s function annotations, it is possible to specify the type of items contained within a homogeneous list (or other collection) for the purpose of type hinting in PyCharm and other IDEs? A pseudo-python code example for a list of int: def my_func(l:list<int>): pass I know it’s possible using Docstring… def my_func(l): “”” :type … Read more
