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列表内部常用功能和使用方法-课堂笔记及课后总结

分类: IT文章 • 2024-10-20 10:16:19

查看列表内部方法，使用help(list)、dir(list)来查看。

1、append：向列表中添加元素，添加到尾部

L.append(object) -- append object to end

1 li = ['parr','123','456']
2 li.append('abc')
3 print(li)
4 
5 #屏幕打印：['parr', '123', '456', 'abc']
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2、count：返回值在列表中出现的次数

L.count(value) -> integer -- return number of occurrences of value

li = ['parr','123','456','123']
result = li.count('123')
print(result)

#屏幕打印：2
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3、extend：扩展对象到列表，对象可以是元组，字符串，列表等

L.extend(iterable) -- extend list by appending elements from the iterable

 1 li = ['parr','123']
 2 li1 = ['789']
 3 tuple1 = ('456')
 4 dic1 = {'k1':'v1'}
 5 li.extend(li1)
 6 print(li)
 7 
 8 #屏幕打印：['parr', '123', '789']
 9 
10 li = ['parr','123']
11 li1 = ['789']
12 tuple1 = ('哈哈')
13 dic1 = {'k1':'v1'}
14 li.extend(tuple1)
15 print(li)
16 
17 #屏幕打印：['parr', '123', '哈', '哈']
18 
19 li = ['parr','123']
20 li1 = ['789']
21 tuple1 = ('哈哈')
22 dic1 = {'k1':'v1'}
23 li.extend(dic1)
24 print(li)
25 
26 #屏幕打印：['parr', '123', 'k1']
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4、index：返回值出现的第一个位置的索引值

L.index(value, [start, [stop]]) -> integer -- return first index of value.

li = ['parr','123','parr']
result = li.index('parr')
print(result)

#屏幕打印：0
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5、insert：插入对象从指定的索引位置开始

L.insert(index, object) -- insert object before index

li = ['parr','123','parr']
result = li.insert(2,'456')
print(li)

#屏幕打印：['parr', '123', '456', 'parr']
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6、pop：删除指定索引的值并返回被删除的值，如果索引未指定默认为最后，索引超出或列表为空会出现索引错误

L.pop([index]) -> item -- remove and return item at index (default last).
Raises IndexError if list is empty or index is out of range.

li = ['parr','123','parr']
result = li.pop()
print(li)
print(result)

#屏幕打印：['parr', '123']
                  parr
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7、remove：删除指定的值第一次出现的位置，也就是说只会删除一次指定的值，如果值不存在会出现ValueError

L.remove(value) -- remove first occurrence of value.
Raises ValueError if the value is not present.

li = ['parr','123','parr']
result = li.pop(1)
print(li)
print(result)

#屏幕打印：['parr', 'parr']
#               123
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 1 li = ['parr','123','parr']
 2 result = li.pop(5)
 3 print(li)
 4 print(result)
 5 
 6 #Index超出范围报错：
 7 #Traceback (most recent call last):
 8 #  File "D:/study/int_class.py", line 24, in <module>
 9 #    result = li.pop(5)
10 #IndexError: pop index out of range
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8、reverse：翻转列表

L.reverse() -- reverse *IN PLACE* 

li = ['parr','456','123']
li.reverse()
print(li)

#屏幕打印：['123', '456', 'parr']
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9、sort：列表排序，字符串和列表不能一起排序，会报错

L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*;

li = [1,2,5,6,9,1,56,12]
li.sort()
print(li)

#屏幕打印：[1, 1, 2, 5, 6, 9, 12, 56]
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注：以上纯属个人课堂笔记及总结，如有错的地方，请大家帮忙纠正，谢谢！

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