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How do I perform the SQL Join equivalent in MongoDB?
...ttps://docs.mongodb.org/master/reference/operator/aggregation/lookup/#pipe._S_lookup
From the docs:
{
$lookup:
{
from: <collection to join>,
localField: <field from the input documents>,
foreignField: <field from the documents of the "from" collection>...
How to remove the querystring and get only the url?
...u can use strtok to get string before first occurence of ?
$url = strtok($_SERVER["REQUEST_URI"], '?');
strtok() represents the most concise technique to directly extract the substring before the ? in the querystring. explode() is less direct because it must produce a potentially two-element arr...
How do I get an animated gif to work in WPF?
...e gif has 10 frames per second.
class GifImage : Image
{
private bool _isInitialized;
private GifBitmapDecoder _gifDecoder;
private Int32Animation _animation;
public int FrameIndex
{
get { return (int)GetValue(FrameIndexProperty); }
set { SetValue(FrameIndexProp...
How to import multiple .csv files at once?
...olutions in other answers using things like do.call(rbind,...), dplyr::bind_rows() or data.table::rbindlist().
If you really want each data frame in a separate object, even though that's often inadvisable, you could do the following with assign:
temp = list.files(pattern="*.csv")
for (i in 1:lengt...
Why use String.Format? [duplicate]
...ing s = string.Format("Hey, {0} it is the {1}st day of {2}. I feel {3}!", _name, _day, _month, _feeling);
vs:
string s = "Hey," + _name + " it is the " + _day + "st day of " + _month + ". I feel " + feeling + "!";
Format Specifiers
(and this includes the fact you can write custom formatters)
...
fork() branches more than expected?
...
when i=0
Process_1: Buffered text= 1 dot
Process_2(created by Process_1): Buffered text= 1 dot
when i=1
Process_3(created by Process_1): Inherit 1 buffered dot from Process_1 and prints 1 dot by itself. In total Process_3 prints 2 dots.
...
Reimport a module in python while interactive
...from the importlib library instead:
import importlib
importlib.reload(some_module)
If you are using python 3.2 or 3.3 you should:
import imp
imp.reload(module)
instead. See http://docs.python.org/3.0/library/imp.html#imp.reload
If you are using ipython, definitely consider using the autor...
Getting the name of a child class in the parent class (static context)
...ot possible. in php4 you could implement a terrible hack (examine the debug_backtrace()) but that method does not work in PHP5. references:
30423
37684
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edit: an example of late static binding in PHP 5.3 (mentioned in comments). note there are potential problems in it's current implementat...
C99 stdint.h header and MS Visual Studio
... Without this header I have no definitions for useful types such as uint32_t, etc.
7 Answers
...
Is cout synchronized/thread-safe?
... @ildjarn - No, @edA-qa mort-ora-y is correct. As long as cout.sync_with_stdio() is true, using cout to output characters from multiple threads without additional synchronization is well-defined, but only on the level of individual bytes. Thus, cout << "ab"; and cout << "cd" exec...