python基础（三）

最新推荐文章于 2024-08-25 07:57:02 发布

Nemophilistf.

最新推荐文章于 2024-08-25 07:57:02 发布

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分类专栏： python 文章标签： python 开发语言

本文链接：https://blog.youkuaiyun.com/weixin_63781898/article/details/125117539

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1.list中所有方法使用

append-给末尾添加一个元素（在原来的列表产生一个新列表）（扩展方式一）

list_data = [1, 2, 3]
list_data.append(4)
print(list_data)
D:\python\python.exe D:/python/python_code/fjq_var.py
[1, 2, 3, 4]

Process finished with exit code 0

clear-清除列表里所有元素

list_data = [1, 2, 3]
list_data.clear()
print(list_data)
D:\python\python.exe D:/python/python_code/fjq_var.py
[]

Process finished with exit code 0

count-统计给定的一个值在列表出现的次数（元组列表都是序列计数方法相同）

list_data = [1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 6, 6]
print(list_data.count(2))
D:\python\python.exe D:/python/python_code/fjq_var.py
2

Process finished with exit code 0

extend-扩展（扩展方式二）

list_data = [1, 2, 3]
list_data.extend('123')
print(list_data)
list_data.extend((4, 5, 6))
print(list_data)
list_data.extend(([7, 8, 9]))
print(list_data)
list_data = [1, 2, 3]
list_data2 = [4, 5, 6]
list_data.extend(list_data2)
print(list_data)

D:\python\python.exe D:/python/python_code/fjq_var.py
[1, 2, 3, '1', '2', '3']
[1, 2, 3, '1', '2', '3', 4, 5, 6]
[1, 2, 3, '1', '2', '3', 4, 5, 6, 7, 8, 9]
[1, 2, 3, 4, 5, 6]

Process finished with exit code 0

index() 函数用于从列表中找出某个值第一个匹配项的索引位置。

该方法返回查找对象的索引位置，如果没有找到对象则抛出异常。

List = ['123', 'abc', 'teacher', 'school']

print("abc索引位置: ", List.index('abc'))
print("123索引位置 : ", List.index( '123', 0, 3 ))
D:\python\python.exe D:/python/python_code/fjq_var.py
abc索引位置:  1
123索引位置 :  0

Process finished with exit code 0

insert-在指定位置放入一个值（扩展方式三）

list_data = [1, 2, 3]
list_data.insert(1, 4)
print(list_data)
list_data = [1, 2, 3]
list_data.insert(2, 4)
print(list_data)
list_data = [1, 2, 3]
list_data.insert(3, 4)
print(list_data)
D:\python\python.exe D:/python/python_code/fjq_var.py
[1, 4, 2, 3]
[1, 2, 4, 3]
[1, 2, 3, 4]

Process finished with exit code 0

pop()函数是将一个LIst里面的最后一个值取出打印返回的时候从List里面删掉。缺省值为-1即如果没有参数就取最后一个值。

list_data = [1, 2, 3]
return_value = list_data.pop()
print(list_data)
print(return_value)
D:\python\python.exe D:/python/python_code/fjq_var.py
[1, 2]
3

Process finished with exit code 0

remove函数可以删除列表中的指定元素

list_fjq = [1, 1, 2, 3]
list_fjq.remove(1)
print(list_fjq)
list_fjq = [1, 1, 2, 3]
list_fjq.remove(2)
print(list_fjq)
list_fjq = [1, 1, 2, 3]
list_fjq.remove(3)
print(list_fjq)
D:\python\python.exe D:/python/python_code/fjq_var.py
[1, 2, 3]
[1, 1, 3]
[1, 1, 2]

Process finished with exit code 0

reverse() 函数用于反向列表中元素（该方法没有返回值，但是会对列表的元素进行反向排序）

list_fjq = [1, 3, 4, 5, 2, "123", '111']
list_fjq.reverse()
print(list_fjq)
D:\python\python.exe D:/python/python_code/fjq_var.py
['111', '123', 2, 5, 4, 3, 1]

Process finished with exit code 0

sort() 函数用于对原列表进行排序

list_fjq = [1, 6, 8, 9, 4, 2, 4, 8, 0, 4, 3]
list_fjq.sort()
print(list_fjq)
D:\python\python.exe D:/python/python_code/fjq_var.py
[0, 1, 2, 3, 4, 4, 4, 6, 8, 8, 9]

Process finished with exit code 0

2. 对["cherry", "litchi", "strawberry", "mangosteen", "pomelo", "pineapple", "pitaya", "durian"]进行默认排序

list_fjq = ["cherry", "litchi", "strawberry", "mangosteen", "pomelo", "pineapple", "pitaya", "durian"]
list_fjq.sort()
print(list_fjq)
D:\python\python.exe D:/python/python_code/fjq_var.py
['cherry', 'durian', 'litchi', 'mangosteen', 'pineapple', 'pitaya', 'pomelo', 'strawberry']

Process finished with exit code 0

对上面的列表使用第三个字母进行排序

def sort_func(x):
    return x[2]
list_fjq = ["cherry", "litchi", "strawberry", "mangosteen", "pomelo", "pineapple", "pitaya", "durian"]
list_fjq.sort(key=sort_func)
print(list_fjq)
D:\python\python.exe D:/python/python_code/fjq_var.py
['cherry', 'pomelo', 'mangosteen', 'pineapple', 'strawberry', 'durian', 'litchi', 'pitaya']

Process finished with exit code 0

3. dict中所有方法的使用

源码和样例

（1）

 clear(self): # real signature unknown; restored from __doc__
        """ D.clear() -> None.  Remove all items from D. """

dict_fjq = {1+1: 2, 2+2: 4}
dict_fjq.clear()
print(dict_fjq)
D:\python\python.exe D:/python/python_code/fjq_var.py
{}

Process finished with exit code 0

（2）

 copy(self): # real signature unknown; restored from __doc__
        """ D.copy() -> a shallow copy of D """

dict_fjq = {1+1: 2, 2+2: 4}
fjq = dict_fjq.copy()
print(dict_fjq, fjq)
D:\python\python.exe D:/python/python_code/fjq_var.py
{2: 2, 4: 4} {2: 2, 4: 4}

Process finished with exit code 0

（3）

get(self, *args, **kwargs): # real signature unknown
        """ Return the value for key if key is in the dictionary, else default. """

dict_fjq = {1+1: 2, 2+2: 4}
fjq = dict_fjq.get(2)
print(dict_fjq, fjq)
D:\python\python.exe D:/python/python_code/fjq_var.py
{2: 2, 4: 4} 2

Process finished with exit code 0

（4）

 items(self): # real signature unknown; restored from __doc__
        """ D.items() -> a set-like object providing a view on D's items """

dict_fjq = {1+1: 2, 2+2: 4}
fjq = dict_fjq.items()
print(dict_fjq, fjq)
D:\python\python.exe D:/python/python_code/fjq_var.py
{2: 2, 4: 4} dict_items([(2, 2), (4, 4)])

Process finished with exit code 0

（5）

keys(self): # real signature unknown; restored from __doc__
        """ D.keys() -> a set-like object providing a view on D's keys """

dict_fjq = {1+1: 2, 2+2: 4}
fjq = dict_fjq.keys()
print(dict_fjq, fjq)
D:\python\python.exe D:/python/python_code/fjq_var.py
{2: 2, 4: 4} dict_keys([2, 4])

Process finished with exit code 0

（6）

pop(self, k, d=None): # real signature unknown; restored from __doc__
        """
        D.pop(k[,d]) -> v, remove specified key and return the corresponding value.
        
        If key is not found, default is returned if given, otherwise KeyError is raised
        """

dict_fjq = {2: 2, 4: 4, 8: 8}
fjq = dict_fjq.pop(2)
print(dict_fjq, fjq)
dict_fjq = {2: 2, 4: 4, 8: 8}
fjq = dict_fjq.pop(4)
print(dict_fjq, fjq)
dict_fjq = {2: 2, 4: 4, 8: 8}
fjq = dict_fjq.pop(8)
print(dict_fjq, fjq)
D:\python\python.exe D:/python/python_code/fjq_var.py
{4: 4, 8: 8} 2
{2: 2, 8: 8} 4
{2: 2, 4: 4} 8

Process finished with exit code 0

（7）

popitem(self, *args, **kwargs): # real signature unknown
        """
        Remove and return a (key, value) pair as a 2-tuple.
        
        Pairs are returned in LIFO (last-in, first-out) order.
        Raises KeyError if the dict is empty.
        """

dict_fjq = {2: 2, 4: 4, 8: 8}
fjq = dict_fjq.popitem()
print(dict_fjq, fjq)




D:\python\python.exe D:/python/python_code/fjq_var.py
{2: 2, 4: 4} (8, 8)

Process finished with exit code 0

（8）

 setdefault(self, *args, **kwargs): # real signature unknown
        """
        Insert key with a value of default if key is not in the dictionary.
        
        Return the value for key if key is in the dictionary, else default.
        """

dict_fjq = {2: 2, 4: 4, 8: 8}
fjq = dict_fjq.setdefault(8)
print(dict_fjq, fjq)
dict_fjq = {2: 2, 4: 4, 8: 8}
fjq = dict_fjq.setdefault(4)
print(dict_fjq, fjq)
dict_fjq = {2: 2, 4: 4, 8: 8}
fjq = dict_fjq.setdefault(2)
print(dict_fjq, fjq)


D:\python\python.exe D:/python/python_code/fjq_var.py
{2: 2, 4: 4, 8: 8} 8
{2: 2, 4: 4, 8: 8} 4
{2: 2, 4: 4, 8: 8} 2

Process finished with exit code 0

（9）

 update(self, E=None, **F): # known special case of dict.update
        """
        D.update([E, ]**F) -> None.  Update D from dict/iterable E and F.
        If E is present and has a .keys() method, then does:  for k in E: D[k] = E[k]
        If E is present and lacks a .keys() method, then does:  for k, v in E: D[k] = v
        In either case, this is followed by: for k in F:  D[k] = F[k]
        """

dict_fjq = {2: 2, 4: 4, 8: 8}
dict_fjq2 = {1: 1, 2: 2, 3: 3}
dict_fjq.update(dict_fjq2)
print(dict_fjq)


D:\python\python.exe D:/python/python_code/fjq_var.py
{2: 2, 4: 4, 8: 8, 1: 1, 3: 3}

Process finished with exit code 0

（10）

values(self): # real signature unknown; restored from __doc__
        """ D.values() -> an object providing a view on D's values """

dict_fjq = {2: 2, 4: 4, 8: 8}
fjq = dict_fjq.values()
print(dict_fjq, fjq)


D:\python\python.exe D:/python/python_code/fjq_var.py
{2: 2, 4: 4, 8: 8} dict_values([2, 4, 8])

Process finished with exit code 0