导图社区 《Python编程 从入门到实践》 第3版 第3章列表简介
《Python编程 从入门到实践》 第3版 第3章列表简介,列表是由一系列按特定顺序排列的元素组成的数据结构。在Python中,列表用方括号[]表示,元素之间用逗号,分隔。
编辑于2024-08-29 19:20:43Python编程 从入门到实践 第3版 第3章 列表简介
3.1 列表是什么
列表(通常起复数名) = ["元素1","元素2"]
由一系列按特定顺序排列的元素组成
bicycles = ['trek','cannondale','redline','specialized'] print(bicycles) →['trek', 'cannondale', 'redline', 'specialized']
3.1.1 访问列表元素
print(bicycles[0])——(列表名[元素索引])
3.1.2 索引从0而不是1开始
要访问第几个元素,用编号减1,写在[]内
"Hello"[3]→l
#提取位置4的字符
特例:访问最后一个元素 倒数第二个元素
print(bicycles[-1]) print(bicycles[-2])
3.1.3 使用列表中的各个值
像使用变量一样
bicycles = ['trek','cannondale','redline','specialized'] messages = f"My first bike was a {bicycles[0].title()}" print(messages) →My first bike was a Trek
3.2 修改、添加和删除元素
3.2.1 修改列表元素
motorcycles = ["honda","yamaha","suzuki"] motorcycles[0] = "ducati" print(motorcycles) →['ducati', 'yamaha', 'suzuki']
3.2.2 在列表中添加元素
在列表末尾添加元素
列表名.append("")
motorcycles = ["honda","yamaha","suzuki"] motorcycles.append("ducati") print(motorcycles) →['honda', 'yamaha', 'suzuki', 'ducati']
在列表中插入元素
列表名.insert(索引,"")
motorcycles = ["honda","yamaha","suzuki"] motorcycles.insert(0,"ducati") print(motorcycles) →['ducati', 'honda', 'yamaha', 'suzuki']
3.2.3 从列表中删除元素
使用del语句删除元素
del(空格)列表名[索引]
可删除任意位置的列表元素,只要知道索引即可
motorcycles = ["honda","yamaha","suzuki"] del motorcycles[1] print(motorcycles) →['honda', 'suzuki']
删除后,使用列表
使用pop()方法删除元素
删除列表末尾的元素,并提取删除的元素
列表名.pop()
1. motorcycles = ["honda","yamaha","suzuki"] 2. popped_motorcycle = motorcycles.pop() 3. print(motorcycles) →['honda', 'yamaha'] 4. print(popped_motorcycle) →suzuki
2. popped_motorcycle (变量名)(删除的摩托车元素)——提取出删除的元素
3. print(motorcycles)——打印删除元素后的列表
4. print(popped_motorcycle)——打印出删除的摩托车元素
删除后,使用提取的元素
删除列表中任意位置的元素
列表名.pop(索引)
根据值删除元素
列表名.remove("元素")
motorcycles = ["honda","yamaha","suzuki","ducati"] motorcycles.remove("ducati") print(motorcycles) →['honda', 'yamaha', 'suzuki']
列表名.remove(变量)
motorcycles = ["honda","yamaha","suzuki","ducati"] too_expensive = "ducati" motorcycles.remove(too_expensive) print(f"A {too_expensive.title()} is too expensive for me.")
too_expensive (变量)= "ducati"(元素)
motorcycles.remove(too_expensive)(变量)
f"A {变量.title()} is too expensive for me."
3.3 管理列表
3.3.1 使用sort()方法对列表进行永久排序
列表名.sort()
motorcycles = ["honda","yamaha","suzuki","ducati"] motorcycles.sort() print(motorcycles)→['ducati', 'honda', 'suzuki', 'yamaha']
倒序——列表名.sort(reverse=True)
布尔运算的“True”必须是大写!小写会提示错误
motorcycles.sort(reverse=True) print(motorcycles)→['yamaha', 'suzuki', 'honda', 'ducati']
3.3.2 使用sorted()函数对列表进行临时排序
变量名=sorted(列表名) print(sorted(列表名))/print(变量名)
motorcycles = ["honda","yamaha","suzuki","ducati"] print(sorted(motorcycles)) →['ducati', 'honda', 'suzuki', 'yamaha']
倒序——变量名=sorted(列表名,reverse=True)
motorcycles = ["honda","yamaha","suzuki","ducati"] daoxu = sorted(motorcycles,reverse=True) print(daoxu)→['yamaha', 'suzuki', 'honda', 'ducati']
3.3.3 永久反向打印列表
不分析元素排序,只是物理上的倒序排列列表中的元素
永久修改元素排序,再次调用reverse()可恢复排序
列表名.reverse()
motorcycles = ["honda","yamaha","suzuki","ducati"] motorcycles.reverse() print(motorcycles)→['ducati', 'suzuki', 'yamaha', 'honda']
3.3.4 确定列表的长度
len(列表名)
motorcycles = ["honda","yamaha","suzuki","ducati"] #len(motorcycles)——可无 print(len(motorcycles))→4
3.4 使用列表时避免索引错误
索引元素需要-1
倒数第一个元素,可以索引[-1] 倒数第二个元素,可以索引[-2]
big_city = ["beijing","shanghai","guangzhou"] print(big_city[-1])→guangzhou
索引错误时,可将列表或其长度打印出来
3.5 小结
print(max(num_list))——打印列表里的 最大值
print(min(num_list))——#打印列表里的 最小值
颜色解释
操作
例子(注解,自己理解)