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Is there a JSON equivalent of XQuery/XPath?
When searching for items in complex JSON arrays and hashes, like:
15 Answers
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NSDate beginning of day and end of day
...onents.timeZone = NSTimeZone(name: "GMT")
– Tom Bevelander
Sep 5 '16 at 0:45
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Specifying rails version to use when creating a new application
I have two versions of rails (2.1.0 and 2.2.2) installed in my computer.
7 Answers
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ab load testing
...
The apache benchmark tool is very basic, and while it will give you a solid idea of some performance, it is a bad idea to only depend on it if you plan to have your site exposed to serious stress in production.
Having said that, here's the most common and simplest ...
Most efficient way to store thousand telephone numbers
...digits left. We view these remaining five digits as 17-bit binary integers and store k of those bits using one method and 17 - k = m with a different method, determining k at the end to minimize the required space.
We first sort the phone numbers (all reduced to 5 decimal digits). Then we count how...
Calculate a Running Total in SQL Server
...QL Server implementation of the Over clause is somewhat limited.
Oracle (and ANSI-SQL) allow you to do things like:
SELECT somedate, somevalue,
SUM(somevalue) OVER(ORDER BY somedate
ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)
AS RunningTotal
FROM Table
SQL Server gi...
C++ unordered_map using a custom class type as the key
... things:
A hash function; this must be a class that overrides operator() and calculates the hash value given an object of the key-type. One particularly straight-forward way of doing this is to specialize the std::hash template for your key-type.
A comparison function for equality; this is require...
How efficient is locking an unlocked mutex? What is the cost of a mutex?
...bunch of mutexes or a single one for an object.
If you have many threads and the access to the object happens often, then multiple locks would increase parallelism. At the cost of maintainability, since more locking means more debugging of the locking.
How efficient is it to lock a mutex? I.e....
How do I find Waldo with Mathematica?
...y' outside of North America] puzzles, using Mathematica (image-processing and other functionality)?
5 Answers
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How does zip(*[iter(s)]*n) work in Python?
...unction call. Therefore you're passing the same iterator 3 times to zip(), and it pulls an item from the iterator each time.
x = iter([1,2,3,4,5,6,7,8,9])
print zip(x, x, x)
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