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Thread Safety in Python's dictionary
...mic operations, there are corner cases where they aren’t atomic (e.g. if __hash__ or __eq__ are implemented as Python methods) and their atomicity should not be relied upon. Neither should you rely on atomic variable assignment (since this in turn depends on dictionaries).
Use the Queue module's Q...
Extracting text OpenCV
...s(cv::Mat img)
{
std::vector<cv::Rect> boundRect;
cv::Mat img_gray, img_sobel, img_threshold, element;
cvtColor(img, img_gray, CV_BGR2GRAY);
cv::Sobel(img_gray, img_sobel, CV_8U, 1, 0, 3, 1, 0, cv::BORDER_DEFAULT);
cv::threshold(img_sobel, img_threshold, 0, 255, CV_THRESH_O...
Where can I learn how to write C code to speed up slow R functions? [closed]
...:
SEXP foobar(){
SEXP ab;
PROTECT(ab = allocVector(STRSXP, 2));
SET_STRING_ELT( ab, 0, mkChar("foo") );
SET_STRING_ELT( ab, 1, mkChar("bar") );
UNPROTECT(1);
}
Using Rcpp, you can write the same function as:
SEXP foobar(){
return Rcpp::CharacterVector::create( "foo", "bar" ) ;
}
...
How do I check if I'm running on Windows in Python? [duplicate]
...lue cannot be determined.
If that isn't working, maybe try platform.win32_ver and if it doesn't raise an exception, you're on Windows; but I don't know if that's forward compatible to 64-bit, since it has 32 in the name.
win32_ver(release='', version='', csd='', ptype='')
Get additional ...
What is the best way to trigger onchange event in react js
... have a value setter in their constructor
if ( inputTypes.indexOf(node.__proto__.constructor) >-1 ) {
const setValue = Object.getOwnPropertyDescriptor(node.__proto__, 'value').set;
const event = new Event('input', { bubbles: true });
setValue.call(node, value);
...
How can strings be concatenated?
...
The easiest way would be
Section = 'Sec_' + Section
But for efficiency, see: https://waymoot.org/home/python_string/
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Why can't non-default arguments follow default arguments?
...wed. A SyntaxError is raised if the arguments are not given in the correct order:
Let us take a look at keyword arguments, using your function.
def fun1(a="who is you", b="True", x, y):
... print a,b,x,y
Suppose its allowed to declare function as above,
Then with the above declarations, we c...
Hidden features of C
...ints to the compiler (common in the Linux kernel)
#define likely(x) __builtin_expect((x),1)
#define unlikely(x) __builtin_expect((x),0)
see: http://kerneltrap.org/node/4705
What I like about this is that it also adds some expressiveness to some functions.
void foo(int arg)
{
if (...
How can I print literal curly-brace characters in python string and also use .format on it?
...
But the order of the keys in a Python object isn't guaranteed... Still, the JSON library is guaranteed to serialise in a JSON way.
– wizzwizz4
Jun 30 '18 at 8:34
...
List of lists changes reflected across sublists unexpectedly
...at you create a new list at each position. One way to do it is
[[1]*4 for _ in range(3)]
which will reevaluate [1]*4 each time instead of evaluating it once and making 3 references to 1 list.
You might wonder why * can't make independent objects the way the list comprehension does. That's beca...