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The tilde operator in Python
...a unary operator (taking a single argument) that is borrowed from C, where all data types are just different ways of interpreting bytes. It is the "invert" or "complement" operation, in which all the bits of the input data are reversed.
In Python, for integers, the bits of the twos-complement repr...
Running unittest with typical test directory structure
...on -m unittest test.test_antigravity.GravityTestCase.test_method
Running all tests:
You can also use test discovery which will discover and run all the tests for you, they must be modules or packages named test*.py (can be changed with the -p, --pattern flag):
$ cd new_project
$ python -m unitte...
Determining 32 vs 64 bit in C++
...esentation. I prefer ENVIRONMENT64 / ENVIRONMENT32. Then I find out what all of the major compilers use for determining if it's a 64 bit environment or not and use that to set my variables.
// Check windows
#if _WIN32 || _WIN64
#if _WIN64
#define ENVIRONMENT64
#else
#define ENVIRONMENT32
#endif...
Hashing a dictionary?
...e hash():
hash(frozenset(my_dict.items()))
This is much less computationally intensive than generating the JSON string or representation of the dictionary.
UPDATE: Please see the comments below, why this approach might not produce a stable result.
...
Logical operators for boolean indexing in Pandas
...Error: The truth value of an array is ambiguous. Use a.empty, a.any() or a.all().
when used as a boolean value. That's because its unclear when it should be True or False. Some users might assume they are True if they have non-zero length, like a Python list. Others might desire for it to be True ...
Find all packages installed with easy_install/pip?
Is there a way to find all Python PyPI packages that were installed with easy_install or pip? I mean, excluding everything that was/is installed with the distributions tools (in this case apt-get on Debian).
...
Python's equivalent of && (logical-and) in an if-statement
... different name in Python.
The logical operators && and || are actually called and and or.
Likewise the logical negation operator ! is called not.
So you could just write:
if len(a) % 2 == 0 and len(b) % 2 == 0:
or even:
if not (len(a) % 2 or len(b) % 2):
Some additional information (...
What's the best UI for entering date of birth? [closed]
...ry fast. For a not so advanced user I suggest using a datepicker. Since usually you also have advanced and non-advanced users I suggest a combination of text input and datepicker.
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How to remove all of the data in a table using Django
...
Inside a manager:
def delete_everything(self):
Reporter.objects.all().delete()
def drop_table(self):
cursor = connection.cursor()
table_name = self.model._meta.db_table
sql = "DROP TABLE %s;" % (table_name, )
cursor.execute(sql)
...
How do I run all Python unit tests in a directory?
...it test module is of the form test_*.py . I am attempting to make a file called all_test.py that will, you guessed it, run all files in the aforementioned test form and return the result. I have tried two methods so far; both have failed. I will show the two methods, and I hope someone out there ...