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Why is “if not someobj:” better than “if someobj == None:” in Python?
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In the first test, Python try to convert the object to a bool value if it is not already one. Roughly, we are asking the object : are you meaningful or not ? This is done using the following algorithm :
If the object has a __nonzero__ special...
Origin null is not allowed by Access-Control-Allow-Origin
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@CiaranG I ran python -m SimpleHTTPServer from a command line and then went to localhost:8000, worked for me. Python comes preinstalled with Mac OS X; you may need to install if using another OS.
– Dave Liepmann
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Handling very large numbers in Python
I've been considering fast poker hand evaluation in Python. It occurred to me that one way to speed the process up would be to represent all the card faces and suits as prime numbers and multiply them together to represent the hands. To whit:
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How do I convert a IPython Notebook into a Python file via commandline?
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If you don't want to output a Python script every time you save, or you don't want to restart the IPython kernel:
On the command line, you can use nbconvert:
$ jupyter nbconvert --to script [YOUR_NOTEBOOK].ipynb
As a bit of a hack, you can even call t...
TypeError: Missing 1 required positional argument: 'self'
I am new to python and have hit a wall. I followed several tutorials but cant get past the error:
6 Answers
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How to make unicode string with python3
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Literal strings are unicode by default in Python3.
Assuming that text is a bytes object, just use text.decode('utf-8')
unicode of Python2 is equivalent to str in Python3, so you can also write:
str(text, 'utf-8')
if you prefer.
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Easy pretty printing of floats in python?
...'d add something potentially useful:
I know you wrote your example in raw Python lists, but if you decide to use numpy arrays instead (which would be perfectly legit in your example, because you seem to be dealing with arrays of numbers), there is (almost exactly) this command you said you made up:...
Import a file from a subdirectory?
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Take a look at the Packages documentation (Section 6.4) here: http://docs.python.org/tutorial/modules.html
In short, you need to put a blank file named
__init__.py
in the "lib" directory.
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How to format a floating number to fixed width in Python
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The format specifier inside the curly braces follows the Python format string syntax. Specifically, in this case, it consists of the following parts:
The empty string before the colon means "take the next provided argument to format()" – in this case the x as the only argument....
Exit codes in Python
...ou can check the special variable $? for the last exit status:
me@mini:~$ python -c ""; echo $?
0
me@mini:~$ python -c "import sys; sys.exit(0)"; echo $?
0
me@mini:~$ python -c "import sys; sys.exit(43)"; echo $?
43
Personally I try to use the exit codes I find in /usr/include/asm-generic/errno.h...