Python knowledge Simple Summary-language Foundation (i)

Basic knowledge of Language basics Pycharm shortcut keys

• Quick Copy

  Cursor navigates to a row or selects many rows Crtl/command + D

• Comments

  The cursor navigates to a line or selects many rows Crtl/command +/

• Delete (cut)

  Cursor navigates to a row or selects many rows Crtl/command + D

Pycharm Simple Setup

• Python template file Settings

  Command +, Editor, code Style, File and Code templaates, Python Script

• Interpreter modification

  Command +, Project:pycharm project, Project interpreter, Project interpreter:

• Installing the Python module
  PS: Another way is to install via PIP.

  Command +, Project:pycharm project, Project interpreter, click on the "+",-> search box to enter the module you want to install, click on the bottom left, and Insta LL Package

First Program

#!/usr/bin/env python#-*- coding:utf-8 -*-#Authour fei.wang#Date:print("hello")

Note:

1，2行为固定的写法（必须），3 4行是规范，标明作者和脚本新建时间。第1行 表示python解释器。第2行 表示脚本的编码格式。

String

Define a string

>>> name = "wangfei">>> print(name)wangfei>>> print(type(name))<class ‘str‘>

string slices

>>> name[0]‘w‘>>> name[1]‘a‘>>> name[0:]‘wangfei‘>>> name[0:4]‘wang‘

Formatting characters

>>> print("name: %s" %name)name: wangfei>>> print("name:{}".format(name))name:wangfei>>> age = 18>>> print("name:{} age:{}".format(name,age))name:wangfei age:18

String built-in functions

StartsWith

>>> cmd = "ifconfig -a">>> cmd.startswith("if")True>>> if cmd.startswith("if"):...     print("ok")... ok

Endswitch

>>> cmd2 = "hellow boy">>> if cmd2.endswith("boy"):...     print("ok")... else:...     print("no")... ok

Replace

>>> cmd2.replace("boy","girl")‘hellow girl‘

Split cut

>>> v = "a.b.c.d.e.f">>> v.split(".")[‘a‘, ‘b‘, ‘c‘, ‘d‘, ‘e‘, ‘f‘]

Join

>>> li = v.split(".")>>> "+".join(li)‘a+b+c+d+e+f‘

List

Features: Ordered repeatable, iterative nesting

>>> li = [1,2,3,4,4]>>> li[0]1>>> li.append("5")>>> li[1, 2, 3, 4, 4, ‘5‘]>>> li.pop()‘5‘>>> li.pop()4>>> li.pop()4>>> li.pop()3 >>> li = [1,2,3,4,4]>>> for iter in li:...     print(iter)... 12344

Dict

Features: unordered, key values, key unique, can be nested

>>> name = {"k1":"v1","k2":"v2","k3":"v3","k4":[1,2,3,4,5,6,7]}>>> name["k1"]‘v1‘>>> name["k4"][1, 2, 3, 4, 5, 6, 7]>>> name["k4"][0]1>>> name["k4"][-1]7>>> name["k5"]="v5">>> name{‘k5‘: ‘v5‘, ‘k2‘: ‘v2‘, ‘k4‘: [1, 2, 3, 4, 5, 6, 7], ‘k3‘: ‘v3‘, ‘k1‘: ‘v1‘}>>> del name["k5"]>>> name{‘k2‘: ‘v2‘, ‘k4‘: [1, 2, 3, 4, 5, 6, 7], ‘k3‘: ‘v3‘, ‘k1‘: ‘v1‘}>>> name["k5"]Traceback (most recent call last):  File "<stdin>", line 1, in <module>KeyError: ‘k5‘>>> for k in name:...     print("key:{},values:{}".format(k,name[k]))... key:k2,values:v2key:k4,values:[1, 2, 3, 4, 5, 6, 7]key:k3,values:v3key:k1,values:v1

Conditional judgment

If

num = 3if num > 2 :    print("{} > 2".format(num))else:    print("{} < 2".format(num))例子：import oscmd = "ifconfig -a"if cmd.startswith("rm"):    print("forbid command.")else:    os.system(cmd)

Cycle

For

for num in range(9):print(num)# break 中止循环for num in range(9):    if num > 8:        break    print(num)# continue 跳出本层循环   for num in range(9):if num == 8:    continueprint(num)

While

import  timewhile True:    time.sleep(2)    print("aaa")

Data structure functions

Definition and execution of functions

def func():    print("hellow")func()

return value of the function

def func():    print("hellow")    return "hellow"# 默认返回是Nonere = func()print(re)

Local variables and global variables

num = 10 # 全局变量def func():    num = 1 # 局部变量    print("hellow")func()

To pass parameters to a function.

# 形式参数def func(name,age):    print("name {},age {}".format(name,age))func("wf","18")# 默认参数def func(name,age=18):    print("name {},age {}".format(name,age))func("wf","27")# 位置参数def func(name,age=18):    print("name {},age {}".format(name,age))func(age = 18,name = "wf")# 传入多参数def func(*args):print(args)for Iter in args:    print(Iter)li = [1,2,3,4,5]    func(*li)# 传入key values def func(**kwargs):print(kwargs["name"],kwargs["age"])msg = {"name":"wf","age":18}func(**msg) # 万能参数def func(*args,**kwargs):print(‘‘‘args:{}kwargs:{}‘‘‘.format(args,kwargs))li = [1,2,3,4]msg = {"name":"wf","age":18}func(*li,**msg)

• Actual combat:

File Cleanup Scripts

import  osdef remove_file(path,tag):for Iter in os.walk(path):    for file in Iter[-1]:        file_abspath = Iter[0] + "/" + file        if file_abspath.endswith("txt"):            print("remove file:{}".format(file_abspath))            #os.remove(file_abspath)if __name__ == "__main__":# path = input("path:> ")path = "/Users/feiwang/PycharmProjects/python-study2/work/test"# tag = input("tag")tag = "txt"remove_file(path,tag)

Decorative Device

def f0(func):    def wrapper(*args,**kwargs):        print("hello")        func()        print("bye")    return wrapper@f0def f1():    print("my name is wf.")f1()

Module

Import Module

import 模块from 模块 import 方法 from 文件夹路径.模块 import 方法from 文件夹路径.模块  import 方法 as 别名

Json

Serialization deserialization

import jsondic = {    "name":"wf",    "age":"18",    "sex":"man",    "salary":20000,    "interest":["read",                "game",                "music"],}re  = json.dumps(dic) # 序列化；把字典变成字符串print(type(re))dic2 = json.loads(re) # 反序列化；把字符串变成字典print(type(dic2))

Example:

Use requests to get JSON-formatted data from the API interface and deserialize it.

import  requestsimport jsonpara = {‘token‘: ‘HPcWR7l4NJNJ‘, ‘name‘: ‘adminset‘}# 参数拼接r = requests.get("http://115.28.147.154/cmdb/get/host/", params = para)data = r.textprint(r.url) # 显示拼接的urld1 = json.loads(data)print(type(d1))

File operations

File open Mode Reference link

Open directly

file = open("url_list.txt","r")# re = file.read # 读取文件所有行# re = file.readline() # 一行一行的读取文件内容re = file.readlines() # 读取所有的文件内容，返回的是一个列表print(re)file.close()

With context processing (recommended)

with open("url_list.txt","r") as file:    # re = file.read # 读取文件所有行    # re = file.readline() # 一行一行的读取    re = file.readlines()  # 读取文件的所有行，返回的是一个列表    print(re)

Liezi:

The content of a log file is processed and the processed content is placed separately into a file.
Requirement: Each time it is opened, it should be processed at the last content location instead of starting from scratch.

from  time import  ctimeimport  osimport  timetag = 0while True:    with open("url_list.txt","rb+") as file ,open("url_list.log","ab+") as log_file:        file.seek(tag) # 挪动文件指针，到指定位置        while True:            line = file.readline()            if line:                new_line = str(ctime()) + "  -  " + str(line,encoding="utf-8")                print(new_line)                log_file.write(bytes(new_line,encoding="utf-8"))            else:                break        tag = file.tell()  # 获取文件指针位置    time.sleep(2)    print("-"*50)

Python knowledge Simple Summary-language Foundation (i)