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Use numpy array in shared memory for multiprocessing
...not available anymore) and @Henry Gomersall's answers. You could use shared_arr.get_lock() to synchronize access when needed:
shared_arr = mp.Array(ctypes.c_double, N)
# ...
def f(i): # could be anything numpy accepts as an index such another numpy array
with shared_arr.get_lock(): # synchroniz...
Is it OK to leave a channel open?
...e it's nondeterministic. Most common related gotcha is too many open files error. You keep opening files... You expect GC to do so... You don't run out of memory (therefore GC doesn't kick in)... You run out of file descriptors at the OS level. OS kills the process :)
– Pijusn
...
How to convert list of tuples to multiple lists?
...
xs, ys = [x for x, y in zs], [y for x, y in zs]
return xs, ys
if __name__ == '__main__':
from timeit import timeit
setup_string='''\
N = 2000000
xs = list(range(1, N))
ys = list(range(N+1, N*2))
zs = list(zip(xs, ys))
from __main__ import t1, t2, t3
'''
print(f'zip:\t\t{timeit(...
git pull while not in a git directory
...a no-op when <path> is empty.
'git -C ""' unhelpfully dies with error "Cannot change to ''", whereas the shell treats cd ""' as a no-op.
Taking the shell's behavior as a precedent, teach git to treat -C ""' as a no-op, as well.
4 years later, Git 2.23 (Q3 2019) documents that 'git ...
How to use glyphicons in bootstrap 3.0
...our code that include the bootstrap and glyphicons CSS? Are you seeing any errors in the browser console?
– Zim
Aug 13 '13 at 10:51
...
decorators in the python standard lib (@deprecated specifically)
...ed
when the function is used."""
@functools.wraps(func)
def new_func(*args, **kwargs):
warnings.simplefilter('always', DeprecationWarning) # turn off filter
warnings.warn("Call to deprecated function {}.".format(func.__name__),
category=DeprecationW...
'typeid' versus 'typeof' in C++
...ecltype doesn't. For example, typeof(int) is int while decltype(int) is an error.
– Shahbaz
Aug 10 '17 at 19:23
1
...
The tilde operator in Python
...s operator.invert. To support this operator in your own class, give it an __invert__(self) method.
>>> import operator
>>> class Foo:
... def __invert__(self):
... print 'invert'
...
>>> x = Foo()
>>> operator.invert(x)
invert
>>> ~x
invert
Any ...
How to base64 encode image in linux bash / shell
...
You need to use cat to get the contents of the file named 'DSC_0251.JPG', rather than the filename itself.
test="$(cat DSC_0251.JPG | base64)"
However, base64 can read from the file itself:
test=$( base64 DSC_0251.JPG )
...
if A vs if A is not None:
...
The statement
if A:
will call A.__nonzero__() (see Special method names documentation) and use the return value of that function. Here's the summary:
object.__nonzero__(self)
Called to implement truth value testing and the built-in operation bool()...