一、python的数据类型
1.python的基本数据类型包括数值数据类型和字符串数据类型；基本数据类型的特点是不允许改变，如果改变基本数据类型的值，会导致内存的重新分配。
2.数值的相互转换函数
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3.变量的三个属性
4.判断某个变量是否是某种类型实例
print(isinstance(3, float)) #False 5.复数类型的使用
a = complex(2,2) b = complex("3+2j") print(a) print(b) print(a+b) print(a-b) print(a*b) print(a/b) (2+2j) (3+2j) (5+4j) (-1+0j) (2+10j) (0.7692307692307692+0.15384615384615388j) 6.python的字符串类型不像Java可以与数值类型相加，如“str”+1会报错，但python支持字符串与数值相乘，表示将字符串重复多少次。
#报错 #print("str"+1)<br> #重复字符串 print("The life is short,i love python\n" * 3) #The life is short,i love python #The life is short,i love python #The life is short,i love python<br> #转为大写 print("lower".upper()) #LOWER<br> #转为小写 print("UPPER".lower()) #upper <br><br>#去除前导和尾部空白 print(" hello python ".strip()) #hello python <br><br>#也可以指定去除的字符 print("##hello python##!".strip("#!")) #hello python <br><br>#求长度 print(len("hello")) #5 <br><br>#拆分字符串 print("orange banana apple".split(" ")) #['orange', 'banana', 'apple'] <br><br>#用指定字符串连接一个列表 print(" ".join(["orange","apple","banana","peach"])) #orange apple banana peach <br><br>#判断字符串是否以某个子串开始 print("good good study".startswith("go")) #True <br><br>#判断字符串是否以某个子串开始 print("day day up".endswith("up")) #True <br><br>#统计子串出现次数 print("Python is a nascent programming language.".count("p")) #1 <br><br>#查找子串出现的下标 print("Sometimes your whole life boils down to one insane move.".find("wh")) #15 <br><br>#判断是否是数字 print("moive".isdigit()) #False <br><br>#判断是否是字母 print("money".isalpha()) #True <br><br>#判断是否是空格 print("i declared".isspace()) #False 7.Python的字符串最强大之处是切片操作
str = "Attitude determines altitude." #取出Attitude（外国人的习惯是左闭右开，即包括左下标，不包括右下标） print(str[0:9]) #Attitude print(str[0:20:3]) #Aiddeis (每3个取一个) print(str[-5:-1]) #tude 8.Python的字符串可以用单引号，双引号，三引号表示，但字符串跨行时只能用三引号或反斜杠
str = '''Be a laborious bee ''' print(str) str1 = "Be \ a \ hard-working \ man" print(str1) #Be a hard-working man 9.实现字符串反转
#切片 str[开始位置：结束位置：步数] 将步数设为-1 def strReverse1(str): return str[::-1] #将字符串转为列表，反转后再连接为字符串 def strReverse2(str): newList = list(str) newList.reverse() return "".join(newList) print(strReverse1("python")) print(strReverse2("python")) 二、输入输出
1、输入函数input()
#输入一个字符串 myStr = input("请输入一个字符串：") print(myStr) #以逗号分割输入多个数 a,b,c = eval(input("请输入3个数:")) print(a,b,c) 2.输出函数 print()
#以逗号分割输出多个变量，输出后显示的分隔符是空格,结尾会输出一个换行符 print("i","am","studying","python") #i am studying python #指定分隔符和结尾符 print("i","am","studying","python",sep="#",end=" ") print() #类似c语言的输出 name = "jackson" age = 22 salary = 5000.0 print("name:%s,age:%d,salary:%.3f" % (name,age,salary)) #python特有的输出形式 print("I like eating {} and {}".format("banana", "pear")) #按位置填充 print("His name is {name} and he is a {sex}".format(sex='male',name='judy')) #按具体名字填充 print("{1} can arm our {0}".format("brain","knowledge")) #按编号填充 print("The happiness rate of chinese citizen is up to {:.3f}".format(0.45)) #设置浮点数输出格式为小数点后三位 print("The population of china is {:,d} million".format(1300)) #千分位用逗号表示 三、集合数据类型
Python的集合数据类型包括列表，元组，字典，集合
1.列表
#四种遍历方式 fruits = ["orange","banana","pear","peach"] for item in fruits: print(item,end=" ") print() for item in iter(fruits): print(item,end=" ") print() for i,item in enumerate(fruits): print(i,"===>",item,end=" ") print() for item in range(len(fruits)): print(fruits[item],end=" ") print() #重复列表四次 print(fruits*4) #['orange', 'banana', 'pear', 'peach', 'orange', 'banana', 'pear', 'peach', 'orange', 'banana', 'pear', 'peach', 'orange', 'banana', 'pear', 'peach'] #列表连接 print(fruits+["pineapple","apple"]) #删除指定下标的元素，不提供参数则删除表尾元素 print(fruits.pop(2)) #['orange', 'banana', 'pear', 'peach', 'pineapple', 'apple'] #追加元素 append追加和extend追加有区别 #append追加的是列表 #extend追加的是元素 fruits.append(["Coconut"]) print(fruits) #['orange', 'banana', 'peach', ['Coconut']] fruits.pop() fruits.extend(["Coconut"]) print(fruits) #['orange', 'banana', 'peach', 'Coconut'] #列表反转 fruits.reverse() print(fruits) #['Coconut', 'peach', 'banana', 'orange'] #指定位置插入 fruits.insert(2, "nothing") print(fruits) #['Coconut', 'peach', 'nothing', 'banana', 'orange'] #删除列表切片 del fruits[1:3] print(fruits) #['Coconut', 'banana', 'orange'] 2.元组
myTuple1 = ("bird","plane","vehicle","subway") #不能对单个元素重新赋值(报错) #myTuple1[0] = "parrot" #但可以对整个元组赋值 myTuple1 = ("python","c++","java") print(myTuple1) #('python', 'c++', 'java') #创建空元组 emptyTuple = () print(emptyTuple) #() #注意创建一个元素的元组要在结尾加逗号 oneTuple = (1) print(oneTuple) #1 不加逗号编译器会认为括号是进行算数运算，而不是创建元组 oneTuple = (1,) print(oneTuple) #(1,) #元组的取值 print(myTuple1[0]) #python print(myTuple1[:]) #('python', 'c++', 'java') print(myTuple1[:1]) #('python',) print(myTuple1[len(myTuple1)-1:]) #('java',) #元组的重复 print(myTuple1 *4) #('python', 'c++', 'java', 'python', 'c++', 'java', 'python', 'c++', 'java', 'python', 'c++', 'java') #元组相加 print(myTuple1 + ("one","two","three")) #('python', 'c++', 'java', 'one', 'two', 'three') 3.字典
myDict = {"one":1,"two":343.33,"three":True} #字典的取值 print(myDict["one"]) #1 #判断键是否存在 print("three" in myDict) #True #更新值 myDict["one"] = 100 print(myDict) #{'one': 100, 'two': 343.33, 'three': True} #清空字典 myDict.clear() print(myDict) #{} 4.集合
#以字符串创建set，自动去除重复元素 mySet = set("hello") print(mySet) #{'o', 'l', 'e', 'h'} #以list创建set mySet1 = set(["a","m","e","o"]) print(mySet1) #{'o', 'a', 'm', 'e'} #以map创建set，值为map的键 mySet2 = set({"name":1,"age":2}) print(mySet2) #{'name', 'age'} #交集 print(mySet & mySet1) #{'e', 'o'} #并集 print(mySet | mySet1) #{'l', 'a', 'e', 'h', 'm', 'o'} #差集 print(mySet - mySet1) #{'l', 'h'} #对称差分运算 print(mySet ^ mySet1) #{'l', 'a', 'h', 'm'} 四、强大的列表解析功能
import random #列表解析 #生成10个随机数，返回一个新列表 list1 = [random.randint(0,100) for i in range(0,10)] for item in list1: print(item,end=" ") #74 38 75 45 96 1 38 93 58 80 print() #求1到20的平方组成的列表 list2 = [i*i for i in range(1,21)] for num in list2: print(num,end=" ") #1 4 9 16 25 36 49 64 81 100 121 144 169 196 225 256 289 324 361 400 #选出list2中的偶数 list3 = [i for i in list2 if i % 2 == 0] for num in list3: print(num) #4 16 36 64 100 144 196 256 324 400 #按行遍历矩阵 list4 = [[1,2,3,4],[5,6,7,8],[2,3,4,5],[6,7,8,9]] list5 = [[1,4,5,6],[2,1,3,4],[3,4,2,1],[7,8,2,1]] print([row for row in list4]) #[[1, 2, 3, 4], [5, 6, 7, 8], [2, 3, 4, 5], [6, 7, 8, 9]] #按列遍历矩阵 print([list4[row][1] for row in range(len(list4))]) #[2, 6, 3, 7] #遍历对角线 print([list4[i][i] for i in range(len(list4))]) # [1, 6, 4, 9] #逐个遍历 print([list4[row][col] for row in range(len(list4)) for col in range(len(list4[row]))]) #[1, 2, 3, 4, 5, 6, 7, 8, 2, 3, 4, 5, 6, 7, 8, 9] #矩阵相加 print([list4[row][col] + list5[row][col] for row in range(list4.__len__()) for col in range(list4[row].__len__())]) #[2, 6, 8, 10, 7, 7, 10, 12, 5, 7, 6, 6, 13, 15, 10, 10] #转置矩阵 print([row for row in zip(*list4)]) #[(1, 5, 2, 6), (2, 6, 3, 7), (3, 7, 4, 8), (4, 8, 5, 9)] #求最大长度对应的字符 students = ["jack","shirely","kangkang","mary"] maxLen = max([len(item) for item in students]) print(maxLen) maxStr = [temp for temp in students if len(temp) == maxLen] print(maxStr) #['kangkang'] 五、内置函数
#几个内置的高阶函数 map,filter,reduce,sorted #map用于将一函数规则应用于一可迭代集合的所有元素 #reduce用于将一函数规则反复作用于一可迭代集合的元素，传入的函数参数必须为两个 #filter将一可迭代集合中适用于函数规则的元素挑选出来 #sorted用于对可迭代集合进行排序 #map的一个栗子(将字符串转为对应数字) #匿名函数求对应字符的数字表示如'0'对应数字0，'1'对应1 f = lambda ch:{"0":0,"1":1,"2":2,"3":3,"4":4,"5":5,"6":6,"7":7,"8":8,"9":9}[ch] #上面函数的功能与这个一样 f1 = lambda ch:int(ch) print(list(map(f,"322"))) #[3, 2, 2] #reduce的一个栗子(将字符串转换为对应的十进制数) def str2Decimal(x,y): return x*10 + y print(reduce(str2Decimal,map(f,"232"))) #232 #filter的一个栗子(使用埃氏筛选法筛选素数) seq = range(2,51) for i in seq: f = lambda x : x == i or x % i seq = list(filter(f,seq)) print(list(seq)) #[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47] #sorted的一个栗子 rules = lambda x:x.lower() reles2 = lambda x:x["age"] students = ["jack","Nacy","Kangkang","asia"] aMap = [{"name":"kangknag","age":25},{"name":"ag","age":13},{"name":"wnag","age":23}] newlist = sorted(students, key=rules, reverse=False) print(sorted(aMap,key=reles2)) #[{'name': 'ag', 'age': 13}, {'name': 'wnag', 'age': 23}, {'name': 'kangknag', 'age': 25}] print(newlist) #['asia', 'jack', 'Kangkang', 'Nacy']