列表内部常用功能和使用方法-课堂笔记及课后总结

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

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

#屏幕打印：['parr', '123', '456', 'abc']

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

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

li = ['parr','123']
li1 = ['789']
tuple1 = ('456')
dic1 = {'k1':'v1'}
li.extend(li1)
print(li)

#屏幕打印：['parr', '123', '789']

li = ['parr','123']
li1 = ['789']
tuple1 = ('哈哈')
dic1 = {'k1':'v1'}
li.extend(tuple1)
print(li)

#屏幕打印：['parr', '123', '哈', '哈']

li = ['parr','123']
li1 = ['789']
tuple1 = ('哈哈')
dic1 = {'k1':'v1'}
li.extend(dic1)
print(li)

#屏幕打印：['parr', '123', 'k1']

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

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']

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    

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 

li = ['parr','123','parr']
result = li.pop(5)
print(li)
print(result)

#Index超出范围报错：
#Traceback (most recent call last):
#  File "D:/study/int_class.py", line 24, in <module>
#    result = li.pop(5)
#IndexError: pop index out of range

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']

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]

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！