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We can create a list simply by creating a list, but with memory limitations, the list size is certainly limited. Also, creating a list of 1 million elements takes up a lot of storage space, and if we just need to access the first few elements, then the vast majority of the space behind it is wasted.So, if the list element can be calculated according to an algorithm, can we continue to calculate the subsequent elements in the process of the loop? This eliminates the need to create a complete list
The database has self-growth fields, but the self-growth fields have their own limitations. Some databases do not support self-growth. In the development process, some customer businesses need to generate business process numbers, and simple numbers cannot meet their needs. Therefore, the idea of writing a serial number generator is generated.
1. First create a database table
Create Table sys_max_number (Mn
the generator *///pycodeobjectpyobject *gi_code;/* List of weak reference. */pyobject *gi_weakreflist;} Pygenobject;gi_running in pygenobject indicates state 0: Not running, 1: running, using Frame.f_lasti==-1 to indicate that it has not been started, because no bytecode has been run, so the last instuction offset of the frame will be -1,gi_ Code corresponding to the generator method, Gi_frame is Pyframeob
iterable object, with iterable, we can rewrite the fab function into a class that supports iterable:
class Fab(object): def __init__(self, max): self.max = max self.n, self.a, self.b = 0, 0, 1 def __iter__(self): return self def next(self): if self.n View Code
The Fab class continuously returns the next number of columns through next (), and the memory usage is always constant:
>>> for n in Fab(5): ... prin
963. [NOI2012] Random number generator★ Import File: randoma.in output file: randoma.out Simple comparisonTime limit: 1 s memory limit: MB"Problem description"The building has recently been fascinated by random algorithms, and random numbers are the basis for generating random algorithms. Building ready to use linear congruential (Linear congruential method) to generate a random sequence, this method needs
We can create a list simply by creating a list, but with memory limitations, the list size is certainly limited. Also, creating a list of 1 million elements takes up a lot of storage space, and if we just need to access the first few elements, then the vast majority of the space behind it is wasted.
So, if the list element can be calculated according to an algorithm, can we continue to calculate the subsequent elements in the process of the loop? This eliminates the need to create a complete li
during next executionTo pass a value in the generator, there is an activation process, and the first time you must use next to trigger the generatorHow to take a value from the generator(1) Next can be stopped at any time, the last one will be an error(2) The For loop is traversed from beginning to end, no break is encountered, return does not stop(3) A strong turn of the list tuple data type will load all
This article is mainly for you in detail how Python uses the generator to achieve the iterative object, has a certain reference value, interested in small partners can refer to, hope to help everyone.
Case Analysis:
A class of an iterative object that iterates over all the primes in a given range:
PN = Number (1, 30)
For k in PN:
Print (k)
The result is: 2
1. What is a generator
With list generation, we can create a list directly. However, with memory limitations, the list capacity is certainly limited. Also, creating a list of 1 million elements takes up a lot of storage space, and if we just need to access the first few elements, the vast majority of the space behind it is wasted. So, if the list element can be calculated according to an algorithm, can we continue to calculate the subsequent elements
963. [NOI2012] random number generator
★ ☆ Input File: randoma.in output file: Randoma.out Simple contrast
time limit: 1 s memory limit: MB
* * "Problem description"
The building has recently been fascinated by random algorithms, and random numbers are the basis for generating random algorithms. Building ready to use linear congruential (Linear congruential method) to generate a random sequence,
With list generation, we can create a list directly. However, with memory limitations, the list capacity is certainly limited. Also, creating a list of 1 million elements takes up a lot of storage space, and if we just need to access the first few elements, the vast majority of the space behind it is wasted.
So, if the list element can be calculated according to an algorithm, can we continue to calculate the subsequent elements in the process of the loop? This eliminates the need to create a co
list to save the intermediate result, but to iterate through the Iterable object, using iterable we can rewrite the FAB function to a class that supports iterable:classFab (object):def __init__(self, max): Self.max=Max SELF.N, SELF.A, self.b= 0, 0, 1def __iter__(self):return SelfdefNext (self):ifSELF.N Self.max:r=self.b self.a, self.b= self.b, SELF.A +self.b SELF.N= SELF.N + 1returnRRaiseStopiteration ()View CodeThe Fab class continuously returns the next n
1. What is a generatorWith list generation, we can create a list directly. However, with memory limitations, the list capacity is certainly limited. Also, creating a list of 1 million elements takes up a lot of storage space, and if we just need to access the first few elements, the vast majority of the space behind it is wasted. So, if the list element can be calculated according to an algorithm, can we continue to calculate the subsequent elements in the process of the loop? This eliminates th
Python generator, python
Here I want to see a line of code
This is a list generator. What if the number we give is not range (10) But range (100000000000000. As we all know, generating a list requires memory usage. If the number
With a list generation, we can create a list directly. However, the list capacity is certainly limited by the memory limit. And, creating a list of 1 million elements, not only takes up a lot of storage space, but if we just need to access the first few elements, the space behind most of the elements is wasted.
So if the list element can be calculated according to some algorithm, can we continue to calculate the subsequent elements in the process of the loop? This eliminates the need to create
"""#-*-coding:cp936-*-# Find all primes in theT=[]def num ():For I in Range (1,501):If i%2!=0:print ' is a prime number ', IPrint num ()#!/usr/bin/python#-*-Coding:utf-8-*-#there is no + + operator in PythonImport stringdef main ():S=raw_input (' Please enter : ')Letter=0Space=0Digit=0Other=0For I in S:If I.isalpha ():Letter+=1Elif I.isspace ():Space+=1Elif I.is
ObjectiveThere is no use of things, there is no deep understanding of things difficult to say that they will, and be asked by others inevitably flawed. Although the previous contact with the concept of Python, but just a glance, the two days of a conversation, others asked the association, suddenly speechless, dead and alive to think of things that have been seen, then suddenly thought of yield, but too late, can only say the concept of unclear, So th
= "Nicholas Zhao Si"
print ("Hip-hop dance" if name == "Nicholas Zhao Si" else "Can't hip-hop dance") One yuan: "Hip-hop dance" Binary: Judgment by if statement Ternary: "No hip-hop dance"
Output results:
Hip-hop
In fact, it is well understood that the if front can be understood as the return result that evaluates to true, else is the return result that evaluates to False, this is the ternary operation.
Ternary operations can also be used in conjunction with list generation,
As you may have heard, the function with yield is called generator (generator) in Python, what is generator?Let's throw away the generator and show the concept of yield with a common programming topic.How to generate Fibonacci columnsThe Fibonacci (Fibonacci)
GeneratorWith a list generation ( [x * x for x in range(10)] for example), we can create a list directly. However, with memory limitations, the list capacity is certainly limited. Also, creating a list of 1 million elements takes up a lot of storage space, and if we just need to access the first few elements, the vast majority of the space behind it is wasted.So, if the list element can be calculated according to an algorithm, can we continue to calculate the subsequent elements in the process o
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