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How to iterate through two lists in parallel?
... And to zip until both iterators are
exhausted, you would use
itertools.zip_longest.
Python 2
In Python 2, zip
returns a list of tuples. This is fine when foo and bar are not massive. If they are both massive then forming zip(foo,bar) is an unnecessarily massive
temporary variable, and should be r...
Are static class variables possible in Python?
...es are one honking great idea -- let's do more of those!
>>> Test.__dict__
{'i': 6, ...}
>>> t.__dict__
{'i': 5}
>>> u.__dict__
{}
Notice how the instance variable t.i got out of sync with the "static" class variable when the attribute i was set directly on t. This is be...
Python: Is it bad form to raise exceptions within __init__?
Is it considered bad form to raise exceptions within __init__ ? If so, then what is the accepted method of throwing an error when certain class variables are initialized as None or of an incorrect type?
...
Calling a class function inside of __init__
...
Call the function in this way:
self.parse_file()
You also need to define your parse_file() function like this:
def parse_file(self):
The parse_file method has to be bound to an object upon calling it (because it's not a static method). This is done by calling t...
Import a file from a subdirectory?
....org/tutorial/modules.html
In short, you need to put a blank file named
__init__.py
in the "lib" directory.
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What is __future__ in Python used for and how/when to use it, and how it works
__future__ frequently appears in Python modules. I do not understand what __future__ is for and how/when to use it even after reading the Python's __future__ doc .
...
How to pass a user defined argument in scrapy spider
...attributes:
class MySpider(scrapy.Spider):
name = 'myspider'
def __init__(self, category='', **kwargs):
self.start_urls = [f'http://www.example.com/{category}'] # py36
super().__init__(**kwargs) # python3
def parse(self, response)
self.log(self.domain) # sys...
Get absolute path of initially run script
...
The correct solution is to use the get_included_files function:
list($scriptPath) = get_included_files();
This will give you the absolute path of the initial script even if:
This function is placed inside an included file
The current working directory is dif...
How to generate keyboard events in Python?
...om ctypes import wintypes
import time
user32 = ctypes.WinDLL('user32', use_last_error=True)
INPUT_MOUSE = 0
INPUT_KEYBOARD = 1
INPUT_HARDWARE = 2
KEYEVENTF_EXTENDEDKEY = 0x0001
KEYEVENTF_KEYUP = 0x0002
KEYEVENTF_UNICODE = 0x0004
KEYEVENTF_SCANCODE = 0x0008
MAPVK_VK_TO_VSC = 0
# ...
Solving “Who owns the Zebra” programmatically?
...all drink different drinks.
# They all smoke different cigarettes.
for vars_ in (colors, nationalities, pets, drinks, cigarettes):
problem.addConstraint(AllDifferentConstraint(), vars_)
# In the middle house they drink milk.
#NOTE: interpret "middle" in a numerical sense (not geometrical)
probl...