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Why can a function modify some arguments as perceived by the caller, but not others?
I'm trying to understand Python's approach to variable scope. In this example, why is f() able to alter the value of x , as perceived within main() , but not the value of n ?
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How to check if an object is a list or tuple (but not string)?
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In python 2 only (not python 3):
assert not isinstance(lst, basestring)
Is actually what you want, otherwise you'll miss out on a lot of things which act like lists, but aren't subclasses of list or tuple.
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What is the use of “assert” in Python?
...condition, and immediately trigger an error if the condition is false.
In Python, it's roughly equivalent to this:
if not condition:
raise AssertionError()
Try it in the Python shell:
>>> assert True # nothing happens
>>> assert False
Traceback (most recent call last):
F...
Inserting a Python datetime.datetime object into MySQL
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J McMahon: time is a Python module.
– dstromberg
Sep 1 '16 at 23:45
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Iterating through a JSON object
..., json_object[0][song].
None of this is specific to JSON. It's just basic Python types, with their basic operations as covered in any tutorial.
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python list in sql query as parameter
I have a python list, say l
15 Answers
15
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Remove all the elements that occur in one list from another
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Python has a language feature called List Comprehensions that is perfectly suited to making this sort of thing extremely easy. The following statement does exactly what you want and stores the result in l3:
l3 = [x for x in ...
Is it possible to have multiple statements in a python lambda expression?
I am a python newbie trying to achieve the following:
17 Answers
17
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How can I read large text files in Python, line by line, without loading it into memory?
... do_something_with(line)
Even better is using context manager in recent Python versions.
with open("log.txt") as fileobject:
for line in fileobject:
do_something_with(line)
This will automatically close the file as well.
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C++模板-继承-具现化 - C/C++ - 清泛网 - 专注C/C++及内核技术
...，这样按照逻辑，每个继承它的子类都应该独享一份静态数据，也就是独享一份父类，这又怎么实现呢？哈哈，正如上面的模式，让基类是模板类，子类继承是采用子类类型作为模板参数，这样在代码编译时不同的继承类就将父...