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Apply a function to every row of a matrix or a data frame
Suppose I have a n by 2 matrix and a function that takes a 2-vector as one of its arguments. I would like to apply the function to each row of the matrix and get a n-vector. How to do this in R?
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Python idiom to return first item or None
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Python 2.6+
next(iter(your_list), None)
If your_list can be None:
next(iter(your_list or []), None)
Python 2.4
def get_first(iterable, default=None):
if iterable:
for item in iterable:
return item
return d...
How to check if variable's type matches Type stored in a variable
...ns.
The is operator does not check if the runtime type of the operand is exactly the given type; rather, it checks to see if the runtime type is compatible with the given type:
class Animal {}
class Tiger : Animal {}
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object x = new Tiger();
bool b1 = x is Tiger; // true
bool b2 = x is Animal; ...
ASP.NET MVC 3: Override “name” attribute with TextBoxFor
Is it possible when using Html.TextBoxFor to override the name attribute?
11 Answers
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Why are C# 3.0 object initializer constructor parentheses optional?
It seems that the C# 3.0 object initializer syntax allows one to exclude the open/close pair of parentheses in the constructor when there is a parameterless constructor existing. Example:
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Using custom std::set comparator
...ying to change the default order of the items in a set of integers to be lexicographic instead of numeric, and I can't get the following to compile with g++:
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Make a negative number positive
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Just call Math.abs. For example:
int x = Math.abs(-5);
Which will set x to 5.
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How can I convert a dictionary into a list of tuples?
... it or organize it as necessary.
See: items(), iteritems()
In Python 3.x, you would not use iteritems (which no longer exists), but instead use items, which now returns a "view" into the dictionary items. See the What's New document for Python 3.0, and the new documentation on views.
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Does JavaScript have a method like “range()” to generate a range within the supplied bounds?
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How to create a self-signed certificate with OpenSSL
I'm adding HTTPS support to an embedded Linux device. I have tried to generate a self-signed certificate with these steps:
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