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列表
列表是最常用的数据类型之一,通过列表可以对数据实现最方便的存储、修改等操作
1.定义列表
fruits = ['apple','banana','orange']
2.通过下标访问列表中的元素,下标从0开始计数
>>> fruits[0] 'apple' >>> fruits[2] 'orange' >>> fruits[-1] 'orange' >>> fruits[-2] 'banana'
3.切片
>>> fruits = ['apple','banana','orange','peal','grape'] >>> fruits[1:4] #取下标1到下标4之间的数,包括1但不包括4 ['banana', 'orange', 'peal'] >>> fruits[1:-1] #取下标1至-1之间的数,不包括-1 ['banana', 'orange', 'peal'] >>> fruits[0:3] #从头开始取,不包括3 ['apple', 'banana', 'orange'] >>> fruits[:3] #和上句一样 ['apple', 'banana', 'orange'] >>> fruits[3:] #从下标3到最后,到末尾只能这样取 ['peal', 'grape'] >>> fruits[0::2] #从头开始,步长为2,即隔一个取一个 ['apple', 'orange', 'grape'] >>> fruits[::2] #和上句一iy ['apple', 'orange', 'grape']
4.追加,append()
>>> fruits ['apple', 'banana', 'orange', 'peal', 'grape'] >>> fruits.append('newpeach') >>> fruits ['apple', 'banana', 'orange', 'peal', 'grape', 'newpeach']
5.插入元素,insert()
在下标1处插入一个西瓜(watermelon)
['apple', 'banana', 'orange', 'peal', 'grape', 'newpeach'] >>> fruits.insert(1,'watermelon') >>> fruits ['apple', 'watermelon', 'banana', 'orange', 'peal', 'grape', 'newpeach']
6.修改列表中的元素
将banana修改为樱桃cherry
>>> fruits ['apple', 'watermelon', 'banana', 'orange', 'peal', 'grape', 'newpeach'] >>> fruits[2]='cherry' >>> fruits ['apple', 'watermelon', 'cherry', 'orange', 'peal', 'grape', 'newpeach']
7.删除
pop()在默认删除最后一个元素后,会返回该元素
>>> fruits ['apple', 'watermelon', 'cherry', 'orange', 'peal', 'grape', 'newpeach'] >>> del fruits[2] #删除第二个元素 >>> fruits ['apple', 'watermelon', 'orange', 'peal', 'grape', 'newpeach'] >>> fruits.remove('orange') #删除指定的元素 >>> fruits ['apple', 'watermelon', 'peal', 'grape', 'newpeach'] >>> fruits.pop() #删除最后一个元素 'newpeach' >>> fruits ['apple', 'watermelon', 'peal', 'grape']
8.扩展 extend()
>>> fruits ['apple', 'watermelon', 'peal', 'grape'] >>> vegetable = ['radish','cabbage','cucumber'] >>> fruits ['apple', 'watermelon', 'peal', 'grape'] >>> vegetable ['radish', 'cabbage', 'cucumber'] >>> fruits.extend(vegetable) >>> fruits ['apple', 'watermelon', 'peal', 'grape', 'radish', 'cabbage', 'cucumber']
9.拷贝 copy()
['apple', 'watermelon', 'peal', 'grape', 'radish', 'cabbage', 'cucumber'] >>> fruits2 = fruits.copy() >>> fruits2 ['apple', 'watermelon', 'peal', 'grape', 'radish', 'cabbage', 'cucumber']
10.统计 count()
>>> fruits.count('apple') 1
11.排序 sort() 和翻转 reverse()
>>> fruits ['apple', 'watermelon', 'peal', 'grape', 'radish', 'cabbage', 'cucumber'] >>> fruits.sort() >>> fruits ['apple', 'cabbage', 'cucumber', 'grape', 'peal', 'radish', 'watermelon'] >>> fruits.reverse() >>> fruits ['watermelon', 'radish', 'peal', 'grape', 'cucumber', 'cabbage', 'apple']
12.获取下标 index()
['watermelon', 'radish', 'peal', 'grape', 'cucumber', 'cabbage', 'apple'] >>> fruits.index('apple') 6 # 只返回找到的第一个下标
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