1.切片
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# 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" |
# 结果输出：
nameList的内容为： ['Willard', 'ChenJD', 'ChenBao', 'ChenXiaoBao', 'hackerLuo']
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nameList前三个元素： ['Willard', 'ChenJD', 'ChenBao']
------------------------------------------------------------------------------
使用切片操作取nameList前三个元素： ['Willard', 'ChenJD', 'ChenBao']
使用切片操作取nameList第二个到第四个元素： ['ChenJD', 'ChenBao', 'ChenXiaoBao', 'hackerLuo']
------------------------------------------------------------------------------
------------------------------------------------------------------------------
数字列表内容为：
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]
------------------------------------------------------------------------------
数字列表前10个数内容： [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
数字列表前10个数内容： [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
数字列表后10个数内容： [20, 21, 22, 23, 24, 25, 26, 27, 28, 29]
数字列表前11-20个数内容： [10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
数字列表前10个数每隔两个取一个： [0, 2, 4, 6, 8]
数字列表前10个数每隔两个取一个： [0, 2, 4, 6, 8]
数字列表每隔3个数取一个： [0, 3, 6, 9, 12, 15, 18, 21, 24, 27]
数字列表内容：
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]
2.迭代
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# 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 = " ") |
# 结果输出：
使用迭代读取dict内容！
personInfoDict的内容： {'name': 'Willard', 'age': 18, 'job': 'Engineer'}
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personInfoDict的key值：
name age jobpersonInfoDict的value值：
Willard 18 EngineerpersonInfoDict的key-value值：
('name', 'Willard') ('age', 18) ('job', 'Engineer')------------------------------------------------------------------------------
------------------------------------------------------------------------------
使用迭代读取字符串内容！
userNameStr的内容： WillardLuo
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userNameStr的每个元素为：
W i l l a r d L u o
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# 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 IterablenameStr = "WillardLuo"nameList = ["Willard","ChenJD","ChenBao"]numberTuple = (1,2,3,4,5)personInfoDict = {"name":"Willard","age":18}number = 100print("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) |
# 结果输出：
判断字符串是否是可迭代对象！
True
判断列表是否是可迭代对象！
True
判断元组是否是可迭代对象！
True
判断字典是否是可迭代对象！
True
判断数字是否是可迭代对象！
False
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0 Willard
1 ChenJD
2 ChenBao
3 ChenXiaoBao
4 hackerLuo
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name Willard
age 18
job Engineer
3.列表生成式
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# 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"]) |
# 结果输出：
numsList的内容： [1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
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列表生成式生成上述列表！
[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
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列表生成式生成1-10偶数的平方的列表
[4, 16, 36, 64, 100]
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列表生成式应用于双重循环
['WC', 'Wh', 'We', 'Wn', 'WJ', 'WD', 'iC', 'ih', 'ie', 'in', 'iJ', 'iD', 'lC', 'lh', 'le', 'ln', 'lJ', 'lD', 'lC', 'lh', 'le', 'ln', 'lJ', 'lD', 'aC', 'ah', 'ae', 'an', 'aJ', 'aD', 'rC', 'rh', 're', 'rn', 'rJ', 'rD', 'dC', 'dh', 'de', 'dn', 'dJ', 'dD']
总结
本篇文章就到这里了，希望能够给你带来帮助，也希望您能够多多关注服务器之家的更多内容!
原文链接：https://fuxi-willard.blog.csdn.net/article/details/122669515
