一篇文章带你学习Python3的高级特性(1)

# 切片：取list或tuple的部分元素
nameList = ["Willard","ChenJD","ChenBao","ChenXiaoBao","hackerLuo"]
print("nameList的内容为：",nameList)
print("------------------------------------------------------------------------------")
# 传统方法取nameList前三个元素
print("nameList前三个元素：",[nameList[0],nameList[1],nameList[2]])
print("------------------------------------------------------------------------------")
# 使用切片取前三个元素，注：切片也是左闭右开
print("使用切片操作取nameList前三个元素：",nameList[0:3])
print("使用切片操作取nameList第二个到第四个元素：",nameList[1:5])
print("------------------------------------------------------------------------------")
print("------------------------------------------------------------------------------")
# 切片的一些常用操作
numsList = list(range(30))
print("数字列表内容为：\n",numsList)
print("------------------------------------------------------------------------------")
print("数字列表前10个数内容：",numsList[0:10])
print("数字列表前10个数内容：",numsList[:10])
print("\n")
print("数字列表后10个数内容：",numsList[-10:])
print("数字列表前11-20个数内容：",numsList[10:20])
print("数字列表前10个数每隔两个取一个：",numsList[0:10:2])
print("数字列表前10个数每隔两个取一个：",numsList[:10:2])
print("数字列表每隔3个数取一个：",numsList[::3])
print("数字列表内容：\n",numsList[:])
# Tips:
# 1.tuple可以使用切片操作，操作的结果仍是tuple;
# (0,1,2,3,4,5)[:3]  ===>  (0,1,2)
# 2.字符串使用切片操作，一个字符就是一个元素
# "Welcome to FUXI Technology."[:3]  ===>  "Wel"

# 给定一个list或tuple，通过for循环来遍历这个list或tuple，这种遍历称为迭代(iteration);# 迭代通过for...in来完成;# 实例1：迭代dictpersonInfoDict = {"name":"Willard","age":18,"job":"Engineer"}print("使用迭代读取dict内容！")print("personInfoDict的内容：",personInfoDict)print("------------------------------------------------------------------------------")# 读取personInfoDict的key值print("personInfoDict的key值：")for key in personInfoDict:    print(key,end = " ")print("\n")print("personInfoDict的value值：")for value in personInfoDict.values():    print(value,end = " ")    print("\n")print("personInfoDict的key-value值：")for item in personInfoDict.items():    print(item,end = " ")print("\n")print("------------------------------------------------------------------------------")print("------------------------------------------------------------------------------")# 实例2：迭代读取字符串userNameStr = "WillardLuo"print("使用迭代读取字符串内容！")print("userNameStr的内容：",userNameStr)print("------------------------------------------------------------------------------")print("userNameStr的每个元素为：")for word in userNameStr:    print(word,end = " ")# 给定一个list或tuple，通过for循环来遍历这个list或tuple，这种遍历称为迭代(iteration);
# 迭代通过for...in来完成;
# 实例1：迭代dict
personInfoDict = {"name":"Willard","age":18,"job":"Engineer"}
print("使用迭代读取dict内容！")
print("personInfoDict的内容：",personInfoDict)
print("------------------------------------------------------------------------------")
# 读取personInfoDict的key值
print("personInfoDict的key值：")
for key in personInfoDict:
    print(key,end = " ")
print("\n")
print("personInfoDict的value值：")
for value in personInfoDict.values():
    print(value,end = " ")
print("\n")
print("personInfoDict的key-value值：")
for item in personInfoDict.items():
    print(item,end = " ")
print("\n")
print("------------------------------------------------------------------------------")
print("------------------------------------------------------------------------------")
# 实例2：迭代读取字符串
userNameStr = "WillardLuo"
print("使用迭代读取字符串内容！")
print("userNameStr的内容：",userNameStr)
print("------------------------------------------------------------------------------")
print("userNameStr的每个元素为：")
for word in userNameStr:
    print(word,end = " ")

# Tips:
# 1.使用for...in循环需要作用于一个可迭代对象；
# 2.判断一个对象是否是可迭代对象，可通过collections.abs模块的Iterable类型判断
from collections.abc import Iterable
nameStr = "WillardLuo"
nameList = ["Willard","ChenJD","ChenBao"]
numberTuple = (1,2,3,4,5)
personInfoDict = {"name":"Willard","age":18}
number = 100
print("判断字符串是否是可迭代对象！")
print(isinstance(nameStr,Iterable))
print("判断列表是否是可迭代对象！")
print(isinstance(nameList,Iterable))
print("判断元组是否是可迭代对象！")
print(isinstance(numberTuple,Iterable))
print("判断字典是否是可迭代对象！")
print(isinstance(personInfoDict,Iterable))
print("判断数字是否是可迭代对象！")
print(isinstance(number,Iterable))
print("------------------------------------------------------------------------------")
print("------------------------------------------------------------------------------")
# 实现对list进行下标循环
# 使用enumerate函数把一个list变成"索引-元素"对
nameList = ["Willard","ChenJD","ChenBao","ChenXiaoBao","hackerLuo"]
for index,value in enumerate(nameList):
    print(index,value)
    
print("------------------------------------------------------------------------------")
willardInfo = {"name":"Willard","age":18,"job":"Engineer"}
# 循环中同时引用两个变量，数据处理中常用
for key,value in willardInfo.items():
    print(key,value)

# 列表生成式：List Comprehensions，用来创建list的生成式
# 实例1：生成[1×1,2×2,3×3,...,10×10]的列表
# 法一：循环
numsList = []
for num in range(1,11):
    numsList.append(num * num)
print("numsList的内容：",numsList)
print("---------------------------------------------------------")
# 法二：列表生成式
print("列表生成式生成上述列表！")
# 把要生成的元素放在前面，后面加循环
print([num * num for num in range(1,11)])
print("---------------------------------------------------------")
# 在循环后添加if判断，筛选1-10中偶数的平方
print("列表生成式生成1-10偶数的平方的列表")
print([num * num for num in range(1,11) if num % 2 == 0])
print("---------------------------------------------------------")
# 双重循环
print("列表生成式应用于双重循环")
print([m + n for m in "Willard" for n in "ChenJD"])