Coder Club

## reduce >>> reduce(lambda x,y: x+y,[1,2,3,4,5]) 15 Please watch carefully. Can you see how it works? Draw a picture: Remember how map works? Forgot? Look at the code: >>> list1 = [1,2,3,4,5,6,7,8,9] >>> list2 = [9,8,7,6,5,4,3,2,1] >>> map(lambda x,y: x+y, list1,list2) [10, 10, 10, 10, 10, 10, 10, 10, 10] ...

Higher order function: simply speaking, one function can receive another function as a parameter. Such a function is called a higher order function The map function will map the specified sequence according to the function provided, that is to say, it will act on the specified sequence Syntax for map(function,interable...) 1 #Use map Fu ...

1. Script example of recursively listing files in directory To list the files in the directory, you can do the following: os.listdir() In [1]: import os In [4]: os.listdir('/root') Out[4]: ['.tcshrc', '.bash_history', '.bashrc', 'ENV', '.cache', '.config', '.cshrc', '.bash_logout', 'python', '.ssh', 'shell', '.bash_profile', '.i ...

Demand: Calculate a string in C x to get the result. For example: "1 + 2 + 66 + 33" The number in the string can be changed, and the number of times to accumulate (here lazy limit to accumulate) can be changed. Ideas / solutions: 1. Use Eval in JavaScript to convert strings into objects for calculation Using Com control calculation me ...

The java.util.concurrent.ExecutorService interface in the Java Concurrency Toolkit defines methods for thread pool task submission, getting thread pool status, and thread pool stop. In JDK 1.8, the shutdown(), shutdown Now (), shutdown() + awaitTermination(long timeout, TimeUnit unit) methods are generally used for thread pool stopping.   1. ...

I. middle and high level functions 1.1 function can do return value #Example: def func(): print(123) def bar(): return func v = bar() v() 1.2 closure Concept: create an area for a function and maintain its own data, which can be easily called later Application scenario: Decorator SQLAlchemy source code #Example: name = 'oldboy' de ...

concept For the concept of thread and process, please refer to the following article: Concurrent / parallel / blocking / non blocking Multi process concept Multithreading concept The above article code uses python, but all concepts and principles are the same; It needs to be emphasized that threads in Java can be executed in parallel on multi-c ...

Method reference and constructor reference As we have known about lambda expressions, there are generally two parts. The left side of the arrow operator (- >) is the parameter list of the lambda body, and the right side is the lambda body. In some cases, the operations in the lambda body can be written in another way, which is shorter.It can ...

Original from: http://www.tanjp.com/archives/135 (immediate fix and update)   Fixed function Functors are the basis of many new features of C + +, such as lambda expressions. However, the std::function provided by STL takes into account too many situations and its performance is not high. Then, the optimization is done, and ...

The application of Lambda expression Call the Collection.sort() method, compare the two employees by custom sorting (first by age, the same age by name), and pass the Lambda as a parameter List<Employee> employees = Arrays.asList( new Employee("Zhang San", 18 ,9999.99), new Employee("Li Si", 50, 5555.99), ...