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Mean per group in a data.frame [duplicate]
... the many ways to specify the variables to act on. Here, vars(-Month) says all variables except Month.
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How do I get Gridview to render THEAD?
...during postback and placed the code in the databound event which addressed all scenarios.
– James Westgate
Jun 10 '15 at 8:12
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Select random row from a sqlite table
... the day seeded with unix epoc for today at noon so it shows the same book all day even if the query is run multiple times. Yes I know caching is more efficient for this use case just an example.
– danielson317
Apr 22 at 17:18
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Knight's Shortest Path on Chessboard
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You have a graph here, where all available moves are connected (value=1), and unavailable moves are disconnected (value=0), the sparse matrix would be like:
(a1,b3)=1,
(a1,c2)=1,
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And the shortest path of two points in a graph can be found usin...
What's the simplest way to test whether a number is a power of 2 in C++?
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so basically (n>0 && ((n & (n-1)) == 0))
– Saurabh Goyal
Jul 10 '16 at 8:06
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The difference between fork(), vfork(), exec() and clone()
...d I expected there to be a huge amount of information on this, but there really wasn't any solid comparison between the four calls.
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Is there any publicly accessible JSON data source to test with real world data? [closed]
..., for example -
A GET request to:
https://api.twitter.com/1/statuses/user_timeline.json?include_entities=true&include_rts=true&screen_name=mralexgray&count=1,
EDIT: Removed due to twitter restricting their API with OAUTH requirements...
{"errors": [{"message": "The Twitter REST API...
Sending command line arguments to npm script
... a parsing library like yargs or minimist; nodejs exposes process.argv globally, containing command line parameter values, but this is a low-level API (whitespace-separated array of strings, as provided by the operating system to the node executable).
Edit 2013.10.03: It's not currently possible...
Making an array of integers in iOS
...rays are such a hassle for anything but trivial, one-off use that it's actually less trouble to wrap any arrays you plan on keeping around as NSArrays of NSNumber.
– Chuck
Jul 27 '10 at 1:58
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Time complexity of Sieve of Eratosthenes algorithm
...oose upper-bound is n(1+1/2+1/3+1/4+1/5+1/6+…1/n) (sum of reciprocals of all numbers up to n), which is O(n log n): see Harmonic number. A more proper upper-bound is n(1/2 + 1/3 + 1/5 + 1/7 + …), that is sum of reciprocals of primes up to n, which is O(n log log n). (See here or here.)
The "find...