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Don't understand why UnboundLocalError occurs (closure) [duplicate]
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Python doesn't have variable declarations, so it has to figure out the scope of variables itself. It does so by a simple rule: If there is an assignment to a variable inside a function, that variable is considered local.[1]...
Python: Continuing to next iteration in outer loop
...there are any built-in ways to continue to next iteration in outer loop in python. For example, consider the code:
8 Answ...
How to add a progress bar to a shell script?
...ch as dd(1), accept a SIGINFO signal, and will report their progress. On Linux systems some commands will respond similarly to SIGUSR1. If this facility is available, you can pipe your input through dd to monitor the number of bytes processed.
Alternatively, you can use lsof to obtain the offset...
Where in a virtualenv does the custom code go?
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virtualenv provides a python interpreter instance, not an application instance. You wouldn't normally create your application files within the directories containing a system's default Python, likewise there's no requirement to locate your applic...
How to convert a dictionary to query string in Python?
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Python 3
urllib.parse.urlencode(query, doseq=False, [...])
Convert a mapping object or a sequence of two-element tuples, which may contain str or bytes objects, to a percent-encoded ASCII text string.
— Pytho...
How to measure time taken between lines of code in python?
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If you want to measure CPU time, can use time.process_time() for Python 3.3 and above:
import time
start = time.process_time()
# your code here
print(time.process_time() - start)
First call turns the timer on, and second call tells you how many seconds have elapsed.
There is also a...
List comprehension vs. lambda + filter
... of filter.
The first is the function call overhead: as soon as you use a Python function (whether created by def or lambda) it is likely that filter will be slower than the list comprehension. It almost certainly is not enough to matter, and you shouldn't think much about performance until you've ...
What's the difference between %s and %d in Python string formatting?
...a string (%s) and number is an integer (%d for decimal).
See https://docs.python.org/3/library/stdtypes.html#printf-style-string-formatting for details.
In Python 3 the example would be:
print('%s %d' % (name, number))
s...
Is there an easy way to pickle a python function (or otherwise serialize its code)?
...a network connection (using asyncore). Is there an easy way to serialize a python function (one that, in this case at least, will have no side affects) for transfer like this?
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Python argparse: How to insert newline in the help text?
I'm using argparse in Python 2.7 for parsing input options. One of my options is a multiple choice. I want to make a list in its help text, e.g.
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