List generation, generators, iterators

A word concept

List Generation--can be calculated directly in the list

Generator-the mechanism by which loops are computed, called Generators: Generator (that is, generating a function or list that is not running, that is, data flow)

The second sentence: the difference between generator and list-generator you do not know the length, is a data stream; list, dict, str you know the length

Iterators-objects that can be called by the next () function and constantly return the next value are called iterators

The second sentence: An iterative object-an object that can act directly on a for loop is called an iterative object: iterable

The third sentence: The generator must be an iterator, the iterator is not necessarily the generator

List-Generated

data = [1,2,2,34for in  data]     # Direct Operation  if  else for in data]     # ternary operation print(data)

Generator

First method, list push-to-type

 for  in range)       # use parentheses to indicate print# at this point only the function memory is printed,

The second complex approach

#斐波那契数列def FOB (num): a    b = 0,1    count = 0 while    count < num:        count + = 1        tmp = b     #也可以写成a, B=b, A+b        B = A + b        a = tmp        yield a     #返回a, while suspending the current function, a returns to the person who called the current function through __next__ ()        # return a    else:p Rint ("Done") F = FOB (1000000) for I in range:    print (f.__next__ ())

　　

Iterators

>>> from Collections Import iterator>>> isinstance ((x to X in range), Iterator) true>>> are Instance ([], Iterator) false>>> isinstance ({}, Iterator) false>>> isinstance (' abc ', Iterator) False

　　

Although the #list, Dict and Str are iterable, they are not iterator. Through the ITER () function, you can change the list, Dict, str and other iterable into Iterator using >>> isinstance (ITER ([]), Iterator) true>>> Isinstance (ITER (' abc '), Iterator) True

　　

List generation, generators, iterators