#1.
#A:当需要的时候，python3的整数类型会自动提供额外的精度用于较大的数值
value0 = 2**100 #value0 = 1267650600228229401496703205376
value1 = 2**100 + 1 #value1 = 1267650600228229401496703205377
#2.
#A:math模块包含数学工具
#B:random模块可以作为随机数字生成器和随机选择器
import math
value = math.pi #value = 3.141592653589793
import random
vlaue = random.random() #vlaue = 0.4847373733624073
value = random.choice([1, 5, 7]) #value = 5
#3.
#A:在python中能够对序列使用反向索引、切片和len()函数来得到长度
#B:序列包括:字符串、列表、元组
#C:切片的时候，:左边默认为0，右边默认为序列长度
#D:在python中，字符串、数字、元组具有不可变性，列表、字典具有可变性
#E:python字符串类型提供了丰富的处理函数
strTem = "string"
value = strTem[-1] #value = 'g'
value = strTem[-len(strTem)] #value = 's'
value = strTem[1:3] #value = 'tr'
#strTem[0] = 's' #运行出错
strTem = "string"
value = strTem.find('in') #value = 3
value = strTem.replace('in', "ab") #value = 'strabg' strTem = 'string'
strTem = "str, abc,num, xyz"
value = strTem.split(', ') #value = ['str', 'abc,num', 'xyz']
value = strTem.split() #value = ['str,', 'abc,num,', 'xyz']
#4.字符串的format()函数
#A:通过位置
value = '{0},{1}'.format('szn',18) #value = 'szn,18'
value = '{},{}'.format('slz',17) #value = 'slz,17'
#B:通过关键字参数
value = '{n0},{n1}'.format(n0=18,n1='szn') #value = '18,szn'
#C:通过下标
listTem0 = ['szn',18]
listTem1 = ['slz',17]
vlaue = '{0[0]},{1[1]}, {1[0]},{0[1]}'.format(listTem0, listTem1) #vlaue = 'szn,17, slz,18'
#D:通过属性
class CPerson:
def __init__(self,name,age):
self.name,self.age = name,age
def __str__(self):
return 'This guy is {self.name},is {self.age} old'.format(self = self)
value = CPerson('szn', 18).__str__() #value = 'This guy is szn,is 18 old'
#E:填充和对齐:^、<、>分别是居中、左对齐、右对齐，后面带宽度 :号后面带填充的字符，只能是一个字符，不指定的话默认是用空格填充
vlaue = '{:>8}'.format('189') #vlaue = ' 189'
vlaue = '{:0>8}'.format('189') #vlaue = '00000189'
vlaue = '{:a>8}'.format('189') #vlaue = 'aaaaa189'
vlaue = '{:a^8}'.format('189') #vlaue = 'aa189aaa'
#F:精度和类型 f、b、d、o、x分别是浮点数、二进制、十进制、八进制、十六进制。用，号还能用来做金额的千位分隔符
value = '{:.2f}'.format(321.33345) #value = '321.33'
value = '{:,d}'.format(123456789) #value = '123,456,789'
value = '0X{:x}'.format(12).upper() #value = '0XC'
value = '{:b}'.format(12) #value = '1100'
value = '{:o}'.format(12) #value = '14'
#5.
#A:ord(), chr()
value = ord('1') #value = 0x31
vlaue = chr(0x31) #vlaue = '1'
#6.
#A:允许在3个引号(单/双引号)中包括多行字符串常量，所有的行都合并在一起，在行末尾添加换行符(实际上这个换行符也是自己敲进去的)
msg = """aaaaa
bbb
'ccc'"""
#msg = "aaaaa\nbbb\n'ccc'"
#7.字符串支持模式匹配(类似正则表达式的功能) 暂不研究
#8.
#A:列表解析
#B:在python中，当最后一次引用对象后，这个对象占用的内存空间将自动被释放掉
listTem = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9]]
value = [row[1] for row in listTem] #value = [2, 5, 8]
value = [listTem[i][i] for i in[0, 1, 2]] #value = [1, 5, 9]
value = (sum(row) for row in listTem)
TemValue = next(value) #TemValue = 6
TemValue = next(value) #TemValue = 15
value = 's' * 2 #value = 'ss'
value = [v * 2 for v in "szn"] #value = ['ss', 'zz', 'nn']
value = [1, 2]
value *= 5 #value = [1, 2, 1, 2, 1, 2, 1, 2, 1, 2]
value = (1, 3)
value *= 5 #value = (1, 3, 1, 3, 1, 3, 1, 3, 1, 3)
value = bool([] or '' or 0 or None) #value = False
#9.
#A:元组具有不可变性，但是其对象可以被改变
tupleTem = (1, 2, 3)
#tupleTem[0] = 0 #报错
tupleTem += (5, 3) #tupleTem = (1, 2, 3, 5, 3)
value = tupleTem.index(1) #value = 0
value = tupleTem.index(3) #value = 2
#value = tupleTem.index(0) #报错
value = tupleTem.count(3) #value = 2
value = tupleTem.count(0) #value = 0
#10.
#A:集合,可以通过set()或者集合常量和表达式创建，是唯一的不可变的对象的无序集合，支持一般的数学集合操作
#B:集合中的项是唯一的，不管将其添加了多少次
#C:集合不能包含可变对象类型，如:列表，字典
#D:集合解析
setA = set("abc") #setA = {'b', 'a', 'c'}
setB = set("bcd")
setTem = setA & setB #setTem = {'b', 'c'}
setTem = setA | setB #setTem = {'b', 'c', 'a', 'd'}
setTem = setA - setB #setTem = {'a'}
setTem = {x ** 2 for x in[1, 2]} #setTem = {1, 4}
vlaue = setA > setB #vlaue = False
setA.add('d') #setA = {'b', 'a', 'c', 'd'}
vlaue = setA > setB #vlaue = True
setB.update(setA) #setB = {'c', 'd', 'b', 'a'}
setB.remove('a') #setB = {'b', 'd', 'c'} remove所操作的元素必须存在，否则会出错
setC = {x ** 2 for x in range(1, 5)}#setC = {16, 1, 9, 4}
#11.
#A:分数模块:Fraction 固定精度浮点数:decimal
from fractions import Fraction #fractions 英[f'rækʃnz]美[f'rækʃnz]n. <数>分数
value = Fraction(1, 3) #value = Fraction(1, 3)
value += Fraction(2, 3) #value = Fraction(1, 1)
import decimal
value = decimal.Decimal('10.222')
value += 1 #value = Decimal('11.222')
decimal.getcontext().prec = 2
value = decimal.Decimal('1') / decimal.Decimal('3') #value = Decimal('0.33')
decimal.getcontext().prec = 5
value = decimal.Decimal('1') / decimal.Decimal('3') #value = Decimal('0.33333')
