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Get the first element of each tuple in a list in Python [duplicate]
...
Use a list comprehension:
res_list = [x[0] for x in rows]
Below is a demonstration:
>>> rows = [(1, 2), (3, 4), (5, 6)]
>>> [x[0] for x in rows]
[1, 3, 5]
>>>
Alternately, you could use unpacking instead of x[0]:
res_li...
How to create a directory if it doesn't exist using Node.js?
...istsSync() isn't deprecated, exists() is though - nodejs.org/api/fs.html#fs_fs_existssync_path
– Ian Chadwick
Oct 18 '16 at 11:04
1
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What's the difference between ES6 Map and WeakMap?
...e: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap):
Keys of WeakMaps are of the type Object only. Primitive data types as
keys are not allowed (e.g. a Symbol can't be a WeakMap key).
Nor can a string, number, or boolean be used as a WeakMap key. A M...
python generator “send” function purpose?
...is an artificial (non-useful) explanatory example:
>>> def double_inputs():
... while True:
... x = yield
... yield x * 2
...
>>> gen = double_inputs()
>>> next(gen) # run up to the first yield
>>> gen.send(10) # goes into 'x' variabl...
Get name of caller function in PHP?
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See debug_backtrace - this can trace your call stack all the way to the top.
Here's how you'd get your caller:
$trace = debug_backtrace();
$caller = $trace[1];
echo "Called by {$caller['function']}";
if (isset($caller['class']))
...
What is Bit Masking?
...esult: 00000101b
Masking is implemented using AND, so in C we get:
uint8_t stuff(...) {
uint8_t mask = 0x0f; // 00001111b
uint8_t value = 0x55; // 01010101b
return mask & value;
}
Here is a fairly common use-case: Extracting individual bytes from a larger word. We define the high-...
How to find if an array contains a specific string in JavaScript/jQuery? [duplicate]
...I've run into this feature as missing in IE7 and IE8, but did not actually test; instead I relied on developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…
– Michael Paulukonis
Jun 19 '13 at 18:21
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Using .sort with PyMongo
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sort should be a list of key-direction pairs, that is
db.test.find({"number": {"$gt": 1}}).sort([("number", 1), ("date", -1)])
The reason why this has to be a list is that the ordering of the arguments matters and dicts are not ordered in Python < 3.6
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What tools are there for functional programming in C?
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FFCALL lets you build closures in C -- callback = alloc_callback(&function, data) returns a function pointer such that callback(arg1, ...) is equivalent to calling function(data, arg1, ...). You will have to handle garbage collection manually, though.
Relatedly, blocks have...
Why is  appearing in my HTML? [duplicate]
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// Tell me the root folder path.
// You can also try this one
// $HOME = $_SERVER["DOCUMENT_ROOT"];
// Or this
// dirname(__FILE__)
$HOME = dirname(__FILE__);
// Is this a Windows host ? If it is, change this line to $WIN = 1;
$WIN = 0;
// That's all I need
?>
<!DOCTYPE html PUBLIC "-//W3C/...