pip install -i https://pypi.tuna.tsinghua.edu.cn/simple requests

pip install ipython

name = 'GitOPEN'
age = 18
salary = 99999.99

aa = bb = cc = 11

dd, ee, ff = 22, 33, "GitOPEN"

In [3]: aa = 1111

In [4]: isinstance(aa, int)
Out[4]: True

# 加法运算
In [5]: 11 + 11
Out[5]: 22

# 减法
In [6]: 5.21 - 5.20
Out[6]: 0.009999999999999787

# 减法
In [10]: 4.3 - 2
Out[10]: 2.3

# 取余
In [11]: 18 % 4
Out[11]: 2

# 乘方
In [12]: 2 ** 5
Out[12]: 32

# 除法，得到一个浮点数
In [13]: 2 / 4
Out[13]: 0.5

# 除法，得到一个整数
In [14]: 2 // 4
Out[14]: 0

# 除法，得到一个整数
In [15]: 5 // 2
Out[15]: 2

In [24]: x = 4.20

In [25]: y = 2.10

In [26]: x + y
Out[26]: 6.300000000000001

In [27]: (x + y) == 6.3
Out[27]: False

In [28]: x = 1.2

In [29]: y = 2.3

In [30]: x + y
Out[30]: 3.5

In [31]: (x + y) == 3.5
Out[31]: True

In [32]: from decimal import Decimal

In [33]: from decimal import getcontext

In [34]: Decimal('4.20') + Decimal('2.10')
Out[34]: Decimal('6.30')

In [35]: x = 4.20

In [36]: y = 2.10

In [37]: z = Decimal(str(x)) + Decimal(str(y))

In [38]: z
Out[38]: Decimal('6.3')

# 设置精度
In [39]: getcontext().prec = 4

In [40]: Decimal('1.00') / Decimal('3.0')
Out[40]: Decimal('0.3333')

In [41]: aa = '我爱学习'

In [42]: bb = '我是张学友的粉丝'

In [44]: aa[1:3]
Out[44]: '爱学'

In [45]: aa[1:4]
Out[45]: '爱学习'

In [47]: bb[-6:-1]
Out[47]: '张学友的粉'

In [48]: bb[-7:-1]
Out[48]: '是张学友的粉'

In [50]: aa + "," + bb
Out[50]: '我爱学习,我是张学友的粉丝'

In [51]: (aa + "," + bb + "。") * 10
Out[51]: '我爱学习,我是张学友的粉丝。我爱学习,我是张学友的粉丝。我爱学习,我是张学友的粉丝。我爱学习,我是张学友的粉丝。我爱学习,我是张学友的粉丝。我爱学习,我是张学友的粉丝。我爱学习,我是张学友的粉丝。我爱学习,我是张学友的粉丝。我爱学习,我是张学友的粉丝。我爱学习,我是张学友的粉丝。'

In [53]: cc = "GitOPEN\niubi"

In [54]: print(cc)
GitOPEN
iubi

In [55]: dd = r"GitOPEN\niubi"

In [56]: print(dd)
GitOPEN\niubi

In [57]: a_list = ['aa', 'bb', 'cc', 'dd', 'ee']

In [58]: b_list = [11, 22, 33.22, 44.05]

In [59]: print(a_list[1])
bb

In [60]: print(a_list[1:3])
['bb', 'cc']

In [61]: print(a_list[2:])
['cc', 'dd', 'ee']

In [62]: print(b_list)
[11, 22, 33.22, 44.05]

# reverse = False表示升序，这是默认值
In [64]: b_list.sort(reverse=False)

In [65]: print(b_list)
[11, 22, 33.22, 44.05]

# reverse = True表示降序
In [66]: b_list.sort(reverse=True)

In [67]: print(b_list)
[44.05, 33.22, 22, 11]

a_tup = ('锄禾','日','当午')
b_tup = (1, 2, 3, 4, 5)
c_tup = "a", "b", "c", "d"

# 创建空元组
d_tup = ()

# 元组中只有一个元素时，需要在元素后面添加逗号
e_tup = (50,)

f_tup = a_tup + b_tup

print(f_tup)

# 删除元组
del f_tup
print(f_tup)

In [69]: a_dict = {'a':'1', 'b':'2', 'c':'3', 'b':'4'}

# 取值
In [70]: a_dict['b']
Out[70]: '4'

In [71]: a_dict
Out[71]: {'a': '1', 'b': '4', 'c': '3'}

# 更新值
In [72]: a_dict['a'] = 11

In [73]: a_dict
Out[73]: {'a': 11, 'b': '4', 'c': '3'}

# 删除某个键对应的值
In [74]: del a_dict['c']

In [75]: a_dict
Out[75]: {'a': 11, 'b': '4'}

# 清空字典中所有的值
In [76]: a_dict.clear()

In [77]: a_dict
Out[77]: {}

# 删除字典
In [78]: del a_dict

In [79]: a_dict
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-79-374973eefd04> in <module>()
----> 1 a_dict

NameError: name 'a_dict' is not defined

def sayhello(text):
    """
    这是一个说你好的函数
    :param text: 打招呼内容
    :return: 返回打招呼内容
    """
    result = "你好，" + text
    return result

sayhelllo('世界')

def printtext(text):
    print(text)
    return;

printtext('你好，世界')
# 报错 TypeError: printtext() missing 1 required positional argument: 'text'
printtext()

def printmsg(text1, text2):
    print('text1是：', text1)
    print('text2是：', text2)
    return


printmsg(text2='世界', text1='你好')

def printemployee(uid, name, salary=1000.00):
    print('Uid:', uid)
    print('Name:', name)
    print('Salary:', salary)
    return


printemployee('001', '张1', 2000.00)
printemployee('002', '张2')

def printinfo(arg1, *args):
    print('输出参数：')
    print('arg1:', arg1)
    for arg in args:
        print('arg', arg)
    return


printinfo(1, 2)
printinfo(3, 4, 5, 6)

sum = lambda x, y: x + y
print(sum(1, 2))

# 全局变量
total = 0

def sum(x, y):
    total = x + y
    print('函数内是局部变量：', total)
    return total

sum(11, 22)
print('函数外是全局变量：', total)

class Employee:
    count = 0

    def __init__(self, name, age):
        self.name = name
        self.age = age
        Employee.count += 1

    def print_count(self):
        print("员工总数为：{}".format(Employee.count))

    def show_info(self):
        print("Name:{},Age:{}".format(self.name, self.age))

    def prt(self):
        print(self)
        print(self.__class__)

# 实例化对象
emp1 = Employee('张三', 18)
# 对象调用方法
emp1.print_count()
emp1.show_info()

emp2 = Employee('张四', 17)
emp2.print_count()
emp2.show_info()

# self是类的实例，代表当前对象的地址；self.__class__指向类。
emp1.prt()

print("Employee.__doc__:", Employee.__doc__)
print("Employee.__name__:", Employee.__name__)
print("Employee.__module__:", Employee.__module__)
print("Employee.__bases__:", Employee.__bases__)
print("Employee.__dict__:", Employee.__dict__)

class Parent:
    parent_attr = 123

    def __init__(self):
        print("Parent构造函数")

    def parentMethod(self):
        print("Parent方法")

    def setAttr(self, attr):
        Parent.parent_attr = attr

    def getAttr(self):
        print("父类属性：", Parent.parent_attr)


class Child(Parent):
    def __init__(self):
        print("子类构造函数")

    def childMethod(self):
        print("Child方法")


child1 = Child()
child1.childMethod()
child1.parentMethod()
child1.setAttr(456)
child1.getAttr()

class A:
    def myMethod(self):
        print("父类方法")


class B(A):
    def myMethod(self):
        print("子类方法")


b = B()
b.myMethod()

import time

ticks = time.time()
print("当前的时间戳为：{}".format(ticks))

import time

localtime = time.localtime(time.time())
print("当前本地时间为：{}".format(localtime))

import time

localtime = time.asctime(time.localtime(time.time()))
print("格式化后的时间为：{}".format(localtime))

import time

# 格式化成2018-08-13 21:55:46形式
print(time.strftime("%Y-%m-%d %H:%M:%S", time.localtime()))

# 格式化成Mon Aug 13 21:52:20 2018形式
print(time.strftime("%a %b %d %H:%M:%S %Y", time.localtime()))

# 将格式字符串转换为时间戳
a = "Mon Aug 13 21:52:20 2018"
print(time.mktime(time.strptime(a, "%a %b %d %H:%M:%S %Y")))

2018-08-13 21:56:49
Mon Aug 13 21:56:49 2018
1534168340.0

import datetime

i = datetime.datetime.now()
print("当前的日期和时间是 %s" % i)
print("ISO格式的日期和时间是 %s" % i.isoformat())
print("当前的年份是 %s" % i.year)
print("当前的月份是 %s" % i.month)
print("当前的日期是  %s" % i.day)
print("dd/mm/yyyy 格式是  %s/%s/%s" % (i.day, i.month, i.year))
print("当前小时是 %s" % i.hour)
print("当前分钟是 %s" % i.minute)
print("当前秒是  %s" % i.second)

import json

data = [{'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5}]

json_str = json.dumps(data)
print(json_str)
print(type(json_str))

data = {'name': 'GitOPEN', 'salary': 70000.01}
json_str = json.dumps(data, sort_keys=True, indent=4, separators=(', ', ': '))
print(json_str)

import json

json_str = '{"a":1,"b":2,"c":3,"d":4,"e":5}'

text = json.loads(json_str)
print(type(text))
print(text)

import csv

with open('data.csv', 'r', encoding='utf-8') as f:
    f_csv = csv.reader(f)
    for row in f_csv:
        print(row)

import csv

with open('data.csv', 'r', encoding='utf-8') as f:
    f_csv = csv.DictReader(f)
    for row in f_csv:
        print(type(row))
        print(row)

import csv

headers = ['Uid', 'Name', 'Age', 'Score']
rows = [
    ('1000', '张1', '18', '99.99'),
    ('1001', '张2', '19', '89.99'),
    ('1002', '张3', '20', '79.99'),
    ('1003', '张4', '21', '69.99')
]
with open('data1.csv', 'w', newline='') as f:
    f_csv = csv.writer(f)
    f_csv.writerow(headers)
    f_csv.writerows(rows)

import csv

headers = ['Uid', 'Name', 'Age', 'Score']
rows = [
    {'Uid': 1000, 'Name': '张1', 'Age': 18, 'Score': 99.99},
    {'Uid': 1001, 'Name': '张2', 'Age': 19, 'Score': 89.99},
    {'Uid': 1002, 'Name': '张3', 'Age': 20, 'Score': 79.99},
    {'Uid': 1003, 'Name': '张4', 'Age': 21, 'Score': 69.99}
]

with open('data2.csv', 'w', newline='') as f:
    f_csv = csv.DictWriter(f, headers)
    f_csv.writeheader()
    f_csv.writerows(rows)