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kernel stack and user space stack
...rence between kernel stack and user stack ?
In short, nothing - apart from using a different location in memory (and hence a different value for the stackpointer register), and usually different memory access protections. I.e. when executing in user mode, kernel memory (part of which is the ker...
How to sort an array of associative arrays by value of a given key in PHP?
... you're looking for is array_multisort().
Here's an example taken straight from the manual and adapted to your case:
$price = array();
foreach ($inventory as $key => $row)
{
$price[$key] = $row['price'];
}
array_multisort($price, SORT_DESC, $inventory);
As of PHP 5.5.0 you can use array_colu...
How to validate an e-mail address in swift?
... doesn't detect email.@invalid.com or email@.invalid.com. The answer below from @alexcristea does
– Ben Sullivan
Nov 23 '16 at 9:42
4
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Fling gesture detection on grid layout
... It is worth noting that you can actually obtain scaled, reasonable values from the system using ViewConfiguration class:
final ViewConfiguration vc = ViewConfiguration.get(getContext());
final int swipeMinDistance = vc.getScaledPagingTouchSlop();
final int swipeThresholdVelocity = vc.getScaledMini...
python assert with and without parenthesis
...rp should be 8, it is 7
Why does this python assert have to be different from everything else:
I think the pythonic ideology is that a program should self-correct without having to worry about the special flag to turn on asserts. The temptation to turn off asserts is too great, and thus it's bei...
Suppressing “is never used” and “is never assigned to” warnings in C#
...code. The first ("... is never used") is usually a code-smell of leftovers from earlier versions of the code. Perhaps code was deleted, but fields left behind.
The second is usually a code-smell for incorrectly used fields. For instance, you might incorrectly write the new value of a property back ...
Is file append atomic in UNIX?
In general, what can we take for granted when we append to a file in UNIX from multiple processes? Is it possible to lose data (one process overwriting the other's changes)? Is it possible for data to get mangled? (For example, each process is appending one line per append to a log file, is it po...
What is the difference between Normalize.css and Reset CSS?
...are actually made more robust) whereas they are visually indistinguishable from normal text after including reset.css. So, normalize.css does not impose a visual starting point (homogeny) upon you. This may not be to everyone's taste. The best thing to do is experiment with both and see which gels w...
Speed up the loop operation in R
... names.
So how better is it?
I run each function for data.frame with nrow from 1,000 to 10,000 by 1,000 and measure time with system.time
X <- as.data.frame(matrix(sample(1:10, n*9, TRUE), n, 9))
system.time(dayloop2(X))
Result is
You can see that your version depends exponentially from nr...
Group by & count function in sqlalchemy
...counting says that for group_by queries it is better to use func.count():
from sqlalchemy import func
session.query(Table.column, func.count(Table.column)).group_by(Table.column).all()
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