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What is the difference between Python's list methods append and extend?
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Actually there's a big difference - x + [4, 5] gives you a new list assigned to x - x.extend() mutates the original list. I elaborate in my answer here below.
– Aaron Hall♦
Jul 17 '17 at 1...
Which is more efficient, a for-each loop, or an iterator?
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If you are just wandering over the collection to read all of the values, then there is no difference between using an iterator or the new for loop syntax, as the new syntax just uses the iterator underwater.
If however, you mean by loop the old "c-style" loop:
for(int i=0; i&l...
Get all attributes of an element using jQuery
I am trying to go through an element and get all the attributes of that element to output them, for example an tag may have 3 or more attributes, unknown to me and I need to get the names and values of these attributes. I was thinking something along the lines of:
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How to smooth a curve in the right way?
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I prefer a Savitzky-Golay filter. It uses least squares to regress a small window of your data onto a polynomial, then uses the polynomial to estimate the point in the center of the window. Finally the window is shifted forward by one data point and the process repeats. This continues until ever...
Concurrent vs serial queues in GCD
...ou wouldn't use either of the last two for long running processes. You normally see it when you're trying to update the UI (always on the main thread) from something that may be running on another thread.
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How to query MongoDB with “like”?
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Actually, it depends. If the query doesn't use an index, and must do a table scan, then it can certainly be expensive. If you're doing a 'starts with' regex query, then that can use an index. Best to run an explain() to see what'...
Why does volatile exist?
...ed 16 bit value as a semaphore to know when the other guy was done. Essentially we did this:
void waitForSemaphore()
{
volatile uint16_t* semPtr = WELL_KNOWN_SEM_ADDR;/*well known address to my semaphore*/
while ((*semPtr) != IS_OK_FOR_ME_TO_PROCEED);
}
Without volatile, the optimizer sees ...
Are tuples more efficient than lists in Python?
...l be more like the tuple example above than the list example, but do you really believe that means performance will be similar?
– mzz
Jan 31 '10 at 15:21
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Find out whether Chrome console is open
... answer. This solution takes advantage of the fact that toString() is not called on logged objects unless the console is open.
var devtools = /./;
devtools.toString = function() {
if (!this.opened) {
alert("Opened");
}
this.opened = true;
}
console.log('%c', devtools);
// devtools.ope...
XMLHttpRequest Origin null is not allowed Access-Control-Allow-Origin for file:/// to file:/// (Serv
I'm trying to create a website that can be downloaded and run locally by launching its index file.
9 Answers
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