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What's the fastest way to merge/join data.frames in R?
... issue? For example I'm guessing that SEM=Scanning electron microscope? Knowing more about the application makes it more interesting to us and helps us prioritise.
– Matt Dowle
Aug 12 '14 at 12:00
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lenses, fclabels, data-accessor - which library for structure access and mutation is better
... putting twice is the same as putting once, or rather, that the second put wins.
put l b1 (put l b2 a) = put l b1 a
Note, that the type system isn't sufficient to check these laws for you, so you need to ensure them yourself no matter what lens implementation you use.
Many of these libraries als...
Java “Virtual Machine” vs. Python “Interpreter” parlance?
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@S.Lott Because it's always good to win arguments with colleagues. ;)
– Qix - MONICA WAS MISTREATED
Oct 6 '14 at 3:50
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Iterator Loop vs index loop [duplicate]
I'm reviewing my knowledge on C++ and I've stumbled upon iterators. One thing I want to know is what makes them so special and I want to know why this:
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How do you convert a byte array to a hexadecimal string, and vice versa?
... faster than {IEnumerable}.Aggregate, for instance, but BitConverter still wins.
Update (2012-04-03)
Added Mykroft's SoapHexBinary answer to analysis, which took over third place.
Update (2013-01-15)
Added CodesInChaos's byte manipulation answer, which took over first place (by a large margin on...
What is in your Mathematica tool bag? [closed]
... of images under these operations, i.e. they're equivalent, using the following
In[3] := SelectEquivalents[ pts, Union[Through[rots[#] ] ]& ] (*<-- Note Union*)
Out[3]:= {{{-1, -1, 0}, {-1, 1, 0}, {1, -1, 0}, {1, 1, 0}},
{{-1, 0, 0}, {0, -1, 0}, {0, 1, 0}, {1, 0, 0}},
{{0...
How do I find where an exception was thrown in C++?
...and often is, located in a different function/method than the point of throwing. It has also been pointed out to me in the comments (thanks Dan) that it is implementation-defined whether or not the stack is unwound before terminate() is called.
Update: I threw together a Linux test program called t...
Should I use tag for icons instead of ? [closed]
...t day to learn twitter's bootstrap and it feels bad that they are not following best practices.
– Jashwant
Jun 21 '12 at 9:35
25
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How do you use bcrypt for hashing passwords in PHP?
... algorithm. You cannot retrieve the plain text password without already knowing the salt, rounds and key (password). [Source]
How to use bcrypt:
Using PHP >= 5.5-DEV
Password hashing functions have now been built directly into PHP >= 5.5. You may now use password_hash() to create a bcrypt h...
What is the performance of Objects/Arrays in JavaScript? (specifically for Google V8)
...n investigation to the question of how implementations behave regarding growing arrays: If they implement them the "usual" way, one would see many quick pushes with rare, interspersed slow pushes at which point the implementation copies the internal representation of the array from one buffer to a l...