一篇文章帶你學習Python3的高級特性(1)

# 切片：取list或tuple的部分元素
nameList = ["Willard","ChenJD","ChenBao","ChenXiaoBao","hackerLuo"]
print("nameList的內容為：",nameList)
print("------------------------------------------------------------------------------")
# 傳統方法取nameList前三個元素
print("nameList前三個元素：",[nameList[0],nameList[1],nameList[2]])
print("------------------------------------------------------------------------------")
# 使用切片取前三個元素，註：切片也是左閉右開
print("使用切片操作取nameList前三個元素：",nameList[0:3])
print("使用切片操作取nameList第二個到第四個元素：",nameList[1:5])
print("------------------------------------------------------------------------------")
print("------------------------------------------------------------------------------")
# 切片的一些常用操作
numsList = list(range(30))
print("數字列表內容為：\n",numsList)
print("------------------------------------------------------------------------------")
print("數字列表前10個數內容：",numsList[0:10])
print("數字列表前10個數內容：",numsList[:10])
print("\n")
print("數字列表後10個數內容：",numsList[-10:])
print("數字列表前11-20個數內容：",numsList[10:20])
print("數字列表前10個數每隔兩個取一個：",numsList[0:10:2])
print("數字列表前10個數每隔兩個取一個：",numsList[:10:2])
print("數字列表每隔3個數取一個：",numsList[::3])
print("數字列表內容：\n",numsList[:])
# Tips:
# 1.tuple可以使用切片操作，操作的結果仍是tuple;
# (0,1,2,3,4,5)[:3]  ===>  (0,1,2)
# 2.字符串使用切片操作，一個字符就是一個元素
# "Welcome to FUXI Technology."[:3]  ===>  "Wel"

# 給定一個list或tuple，通過for循環來遍歷這個list或tuple，這種遍歷稱為迭代(iteration);# 迭代通過for...in來完成;# 實例1：迭代dictpersonInfoDict = {"name":"Willard","age":18,"job":"Engineer"}print("使用迭代讀取dict內容！")print("personInfoDict的內容：",personInfoDict)print("------------------------------------------------------------------------------")# 讀取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("------------------------------------------------------------------------------")# 實例2：迭代讀取字符串userNameStr = "WillardLuo"print("使用迭代讀取字符串內容！")print("userNameStr的內容：",userNameStr)print("------------------------------------------------------------------------------")print("userNameStr的每個元素為：")for word in userNameStr:    print(word,end = " ")# 給定一個list或tuple，通過for循環來遍歷這個list或tuple，這種遍歷稱為迭代(iteration);
# 迭代通過for...in來完成;
# 實例1：迭代dict
personInfoDict = {"name":"Willard","age":18,"job":"Engineer"}
print("使用迭代讀取dict內容！")
print("personInfoDict的內容：",personInfoDict)
print("------------------------------------------------------------------------------")
# 讀取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("------------------------------------------------------------------------------")
# 實例2：迭代讀取字符串
userNameStr = "WillardLuo"
print("使用迭代讀取字符串內容！")
print("userNameStr的內容：",userNameStr)
print("------------------------------------------------------------------------------")
print("userNameStr的每個元素為：")
for word in userNameStr:
    print(word,end = " ")

# Tips:
# 1.使用for...in循環需要作用於一個可迭代對象；
# 2.判斷一個對象是否是可迭代對象，可通過collections.abs模塊的Iterable類型判斷
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("判斷字符串是否是可迭代對象！")
print(isinstance(nameStr,Iterable))
print("判斷列表是否是可迭代對象！")
print(isinstance(nameList,Iterable))
print("判斷元組是否是可迭代對象！")
print(isinstance(numberTuple,Iterable))
print("判斷字典是否是可迭代對象！")
print(isinstance(personInfoDict,Iterable))
print("判斷數字是否是可迭代對象！")
print(isinstance(number,Iterable))
print("------------------------------------------------------------------------------")
print("------------------------------------------------------------------------------")
# 實現對list進行下標循環
# 使用enumerate函數把一個list變成"索引-元素"對
nameList = ["Willard","ChenJD","ChenBao","ChenXiaoBao","hackerLuo"]
for index,value in enumerate(nameList):
    print(index,value)
    
print("------------------------------------------------------------------------------")
willardInfo = {"name":"Willard","age":18,"job":"Engineer"}
# 循環中同時引用兩個變量，數據處理中常用
for key,value in willardInfo.items():
    print(key,value)

# 列表生成式：List Comprehensions，用來創建list的生成式
# 實例1：生成[1×1,2×2,3×3,...,10×10]的列表
# 法一：循環
numsList = []
for num in range(1,11):
    numsList.append(num * num)
print("numsList的內容：",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，後面加循環
print([num * num for num in range(1,11)])
print("---------------------------------------------------------")
# 在循環後添加if判斷，篩選1-10中偶數的平方
print("列表生成式生成1-10偶數的平方的列表")
print([num * num for num in range(1,11) if num % 2 == 0])
print("---------------------------------------------------------")
# 雙重循環
print("列表生成式應用於雙重循環")
print([m + n for m in "Willard" for n in "ChenJD"])