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Version number comparison in Python
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Note cmp() has been removed in Python 3: docs.python.org/3.0/whatsnew/3.0.html#ordering-comparisons
– Dominic Cleal
May 12 '14 at 12:59
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Any reason not to use '+' to concatenate two strings?
A common antipattern in Python is to concatenate a sequence of strings using + in a loop. This is bad because the Python interpreter has to create a new string object for each iteration, and it ends up taking quadratic time. (Recent versions of CPython can apparently optimize this in some cases, b...
I need to securely store a username and password in Python, what are my options?
I'm writing a small Python script which will periodically pull information from a 3rd party service using a username and password combo. I don't need to create something that is 100% bulletproof (does 100% even exist?), but I would like to involve a good measure of security so at the very least it w...
Python strptime() and timezones?
...cond). Nothing else. No mention of timezones.
Interestingly, [Win XP SP2, Python 2.6, 2.7] passing your example to time.strptime doesn't work but if you strip off the " %Z" and the " EST" it does work. Also using "UTC" or "GMT" instead of "EST" works. "PST" and "MEZ" don't work. Puzzling.
It's wor...
How many classes should I put in one file? [closed]
I'm used to the Java model where you can have one public class per file. Python doesn't have this restriction, and I'm wondering what's the best practice for organizing classes.
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How do I get current URL in Selenium Webdriver 2 Python?
...e's a command called getLocation for ruby, but I can't find the syntax for Python.
4 Answers
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How to define a two-dimensional array?
...ou have to first initialize the outer list with lists before adding items; Python calls this
"list comprehension".
# Creates a list containing 5 lists, each of 8 items, all set to 0
w, h = 8, 5;
Matrix = [[0 for x in range(w)] for y in range(h)]
You can now add items to the list:
Matrix[0][0] =...
How do I check that multiple keys are in a dict in a single pass?
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if {"foo", "bar"} <= myDict.keys(): ...
If you're still on Python 2, you can do
if {"foo", "bar"} <= myDict.viewkeys(): ...
If you're still on a really old Python <= 2.6, you can call set on the dict, but it'll iterate over the whole dict to build the set, and that's slow:
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What do I use for a max-heap implementation in Python?
Python includes the heapq module for min-heaps, but I need a max heap. What should I use for a max-heap implementation in Python?
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Show the progress of a Python multiprocessing pool imap_unordered call?
... @HananShteingart: It works fine on my system (Ubuntu) with both Python 2 and 3. I've used def do_word(*a): time.sleep(.1) as an example. If it doesn't work for you then create a complete minimal code example which demonstrates your issue: describe using words what do you expect to happen ...