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How to sort a dataframe by multiple column(s)

...as speedy as the base R commands with their convoluted machinations. Typically brilliant Hadley Wickham work. My only gripe with it is that it breaks the standard R nomenclature where sorting objects get called by sort(object), but I understand why Hadley did it that way due to issues discussed in...
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Override compile flags for single files

... It would be preferable to use add_compile_options add_compile_options(-Wall -Weffc++ -pedantic -std=c++0x) or for CMake versions < 3.0 to do something more like: set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Weffc++ -pedantic -std=c++0x") In response to further questions in the comment...
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What's the false operator in C# good for?

...rride |, &, true and false in exactly the right way the compiler will call | and & when you write || and &&. For example, look at this code (from http://ayende.com/blog/1574/nhibernate-criteria-api-operator-overloading - where I found out about this trick; archived version by @Biggs...
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C# version of java's synchronized keyword?

... be thread-safe. Use YAGNI: only apply thread-safety when you know you actually are going to use it (and test it). For the method-level stuff, there is [MethodImpl]: [MethodImpl(MethodImplOptions.Synchronized)] public void SomeMethod() {/* code */} This can also be used on accessors (properties ...
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What's the point of having pointers in Go?

I know that pointers in Go allow mutation of a function's arguments, but wouldn't it have been simpler if they adopted just references (with appropriate const or mutable qualifiers). Now we have pointers and for some built-in types like maps and channels implicit pass by reference. ...
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GCD to perform task in main thread

I have a callback which might come from any thread. When I get this callback, then I would like to perform a certain task on the main thread. ...
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Logging request/response messages when using HttpClient

... intercepts the request before it handles it to HttpClientHandler which finally writes to the wire. PostAsJsonAsync extension internally creates an ObjectContent and when ReadAsStringAsync() is called in the LoggingHandler, it causes the formatter inside ObjectContent to serialize the object and tha...
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How can I transform string to UTF-8 in C#?

...hould also write Console.OutputEncoding = System.Text.Encoding.UTF8;!!! Or all utf8 strings will be outputed as gbk... share | improve this answer | follow | ...
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git: Apply changes introduced by commit in one repo to another repo

...om, and generate patches from commits you want with git format-patch Optionally, copy patches (0001-* etc.) to your repository Use git am --3way to apply patches share | improve this answer ...
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Database cluster and load balancing

What is database clustering? If you allow the same database to be on 2 different servers how do they keep the data between synchronized. And how does this differ from load balancing from a database server perspective? ...