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For each row in an R dataframe
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Be careful, as the dataframe is converted to a matrix, and what you end up with (x) is a vector. This is why the above example has to use numeric indexes; the by() approach gives you a data.frame, which makes your code more robust.
– D...
What is meant with “const” at end of function declaration? [duplicate]
...al function taking an implicit this pointer. So a method int Foo::Bar(int random_arg) (without the const at the end) results in a function like int Foo_Bar(Foo* this, int random_arg), and a call such as Foo f; f.Bar(4) will internally correspond to something like Foo f; Foo_Bar(&f, 4). Now addin...
Expand/collapse section in UITableView in iOS
Could somebody tell me the way to perform UITableView expandable/collapsible animations in sections of UITableView as below?
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Try-catch speeding up my code?
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One of the Roslyn engineers who specializes in understanding optimization of stack usage took a look at this and reports to me that there seems to be a problem in the interaction between the way the C# compiler generates local variable stores and the way the JIT compiler does re...
Capture screenshot of active window?
I am making a screen capturing application and everything is going fine. All I need to do is capture the active window and take a screenshot of this active window. Does anyone know how I can do this?
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What are the disadvantages to declaring Scala case classes?
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First the good bits:
Everything immutable by default
Yes, and can even be overridden (using var) if you need it
Getters automatically defined
Possible in any class by prefixing params with val
Decent toString() implementation
Yes, very useful, but doable by hand on any class if nece...
Is there a Python equivalent of the C# null-coalescing operator?
... so it works in a boolean context. If the values are not boolean, they are converted to boolean for the purposes of the operator.
Note that the or operator does not return only True or False. Instead, it returns the first operand if the first operand evaluates to true, and it returns the second ope...
What does -> mean in Python function definitions?
...to attach a metadata string to various types of object. This is amazingly handy, so Python 3 extends the feature by allowing you to attach metadata to functions describing their parameters and return values.
There's no preconceived use case, but the PEP suggests several. One very handy one is to al...
What is the relative performance difference of if/else versus switch statement in Java?
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That's micro optimization and premature optimization, which are evil. Rather worry about readabililty and maintainability of the code in question. If there are more than two if/else blocks glued together or its size is unpredictable, then you may high...
Best way to extract a subvector from a vector?
... +1, also it's O(Y-X), which is less than or equal to O(N) (and in his example much less)
– orip
Jan 7 '09 at 21:53
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