Python4: Advanced Features

4 Advanced Features 4.1 slices [:]

　　* Note:--list and tuple, string all support slicing

4.2 Iterations iteration for ... in and for ... in if

Two variable iterations,

 for inch [(1, 1), (2, 4), (3, 9)]: Results 1 1--2 4--3 9
Example 2: Dictionary >>>d={' x ': ' A ', ' y ': ' B ', ' z ': ' C '} >>> for k,v in D.items (): or [k + ' = ' + V for K, V in D.items ()]
   
     result y = B--x = A--z = C
   

4.3 List-generated

 for inch if  for inch ' ABC '  for inch ' XYZ ']

4.4 Generator Generator

-function: When large amounts of data are processed, one side of the loop is computed; Note: To iterate through the print element with a in loop instead of next ()
Example: Fibonacci sequence:

def= 0, 0, 1 while n < Max:yield= b, A += n + 1

Two methods are created:
1. Change from list to: Change a list-generated [] to ();
2. Change from function to: return result using yield statement instead of return statement;
　　* NOTE: The yield statement returns one result at a time, in the middle of each result, suspends the state of the function so that the next time it is left to continue execution, and the generator's only note is that the generator can only traverse once
Yield image analogy: Squeeze toothpaste, from the outside every call, "squeeze" out a line, processing and then "squeeze" out of the next line, and then processing, here said the "squeeze" is yield.
About yield usage and method: https://www.ibm.com/developerworks/cn/opensource/os-cn-python-yield/

Python4: Advanced Features