Python High-order functions

1. The function itself can also be assigned to a variable, that is: A variable can point to a function. The function name is actually a variable pointing to the function!

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2. A variable can point to a function , The function's parameters can receive the variable , then a function can receive another function as a parameter , This function is called the higher order function .

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the 3.map () function receives two parameters , One is a function , the other is a sequence , and a map Functions the passed-in function sequentially to each element of the sequence and returns the result as a new list

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4. Thereduce function uses a function to sequence in a column [X1, x2, x3 ...] , the function must receive two parameters, and reduce accumulates the result and the next element of the sequence.

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 5. filter () also receives a function and a sequence. and map () different time ,filter () the incoming function is applied sequentially to each element true or false decide whether to keep or discard the element.

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Sorted reverse Order

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* Anonymous functions have only one expression , don't write . return, The return value is the result of the expression.

* Because anonymous functions have no name , There is no need to worry about function name collisions. the anonymous function is also a function object , You can assign an anonymous function to a variable , and then use the variable to invoke the function.

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* The anonymous function can also be returned as a return value

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8. adorners are used to decorate functions.

Want to enhance the function of the original function;

But you do not want to modify the definition of the now () function;

How you dynamically add functionality while your code is running

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Python High-order functions