key is a function that will be called to transform the collection’s items before they are compared. The parameter passed to key must be something that is callable. The use of lambda creates an anonymous function (which is callable). In the case of sorted the callable only takes one parameters. Python’s lambda is pretty simple. It can only do and return one thing really. … Read more
On Python 3.4+ you can use statistics.mean() On older versions of Python you can do On Python 2 you need to convert len to a float to get float division There is no need to use reduce. It is much slower and was removed in Python 3.
I find that if you’re familiar with SQL syntax, using the LINQ query syntax is much clearer, more natural, and makes it easier to spot errors: If you’re really stuck on using lambdas though, your syntax is quite a bit off. Here’s the same query, using the LINQ extension methods:
std::function is a type erasure object. That means it erases the details of how some operations happen, and provides a uniform run time interface to them. For std::function, the primary1 operations are copy/move, destruction, and ‘invocation’ with operator() — the ‘function like call operator’. In less abstruse English, it means that std::function can contain almost any object that acts like a function … Read more
There is statement that the compiler can’t pass. I can’t understand it. Can anyone tell me in detail or How to fix it ? Best wishes to you. The statement as follow: The compiler given the information as follow: The std::priority_queue inducted in cppreference site:http://en.cppreference.com/w/cpp/container/priority_queue mainly structure as follow:
The problem C++ includes useful generic functions like std::for_each and std::transform, which can be very handy. Unfortunately they can also be quite cumbersome to use, particularly if the functor you would like to apply is unique to the particular function. If you only use f once and in that specific place it seems overkill to … Read more