【四】Python基础之数据结构：列表
列表
序列是Python中最基本的数据结构。序列中的每个元素都分配一个数字 - 它的位置，或索引，第一个索引是0，第二个索引是1，依此类推。Python有6个序列的内置类型，但最常见的是列表和元组。序列都可以进行的操作包括索引，切片，加，乘，检查成员。
列表基本操作：索引、切片、追加、删除、长度、循环、包含
创建列表：
1 2 3 | name_list = ['alex', 'seven', 'eric'] 或 name_list ＝ list(['alex', 'seven', 'eric']) |
|---|
Python列表脚本操作符
列表对 + 和 * 的操作符与字符串相似。+ 号用于组合列表，* 号用于重复列表。
如下所示：
Python 表达式 | 结果 | 描述 |
|---|---|---|
len([1, 2, 3]) | 3 | 长度 |
[1, 2, 3] + [4, 5, 6] | [1, 2, 3, 4, 5, 6] | 组合 |
['Hi!'] * 4 | ['Hi!', 'Hi!', 'Hi!', 'Hi!'] | 重复 |
3 in [1, 2, 3] | True | 元素是否存在于列表中 |
for x in [1, 2, 3]: print(x, end=" ") | 1 2 3 | 迭代 |
Python列表截取与拼接
Python的列表截取与字符串操作类型，如下所示：
L=['Google', 'Runoob', 'Taobao']
操作：
Python 表达式 | 结果 | 描述 |
|---|---|---|
L[2] | 'Taobao' | 读取第三个元素 |
L[-2] | 'Runoob' | 从右侧开始读取倒数第二个元素: count from the right |
L[1:] | ['Runoob', 'Taobao'] | 输出从第二个元素开始后的所有元素 |
Python列表函数&方法
Python包含以下函数:
序号 | 函数 |
|---|---|
1 | len(list)列表元素个数 |
2 | max(list)返回列表元素最大值 |
3 | min(list)返回列表元素最小值 |
4 | list(seq)将元组转换为列表 |
Python包含以下方法:
序号 | 方法 |
|---|---|
1 | list.append(obj)在列表末尾添加新的对象 |
2 | list.count(obj)统计某个元素在列表中出现的次数 |
3 | list.extend(seq)在列表末尾一次性追加另一个序列中的多个值（用新列表扩展原来的列表） |
4 | list.index(obj)从列表中找出某个值第一个匹配项的索引位置 |
5 | list.insert(index, obj)将对象插入列表 |
6 | list.pop([index=-1]])移除列表中的一个元素（默认最后一个元素），并且返回该元素的值 |
7 | list.remove(obj)移除列表中某个值的第一个匹配项 |
8 | list.reverse()反向列表中元素 |
9 | list.sort(cmp=None, key=None, reverse=False)对原列表进行排序 |
10 | list.clear()清空列表 |
11 | list.copy()复制列表 |
列表是有序的，元素可以被修改
test = [11, 22, 33, 44, 55, 22]
################################## List 列表之删除元素 ####################################1 2 3 | del test[1] # 切片删除 del test[1:4] # 删除test[1] ，test[2]，test[3] test.clear() # clear方法，清空test列表中的所有元素，变为空列表 test[] |
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列表增加
insert、extend、append
列表删除
pop、remove、clear、del
列表统计
len、count
列表排序
reveser、sort、index
# pop方法，弹出test列表指定位置的元素，弹出的元素可以用变量接收
# pop(self, index=None) 参数：index:待弹出元素的下标(可以为空,为空时默认弹出列表最后一个元素)
# v = test.pop(1)
# remove方法，删除(默认从左往右删除第一个符合要求的value，后面符合要求的value不删除)
# remove(self, value) 参数：value：待删除元素
# test.remove(22)
################################## List 列表之增加元素 ####################################
# append方法，在test列表末尾增加一个元素
# append(self, p_object) 参数：p_object:待添加的元素
# test.append(66)
# test.append([77, 88])
# extend方法，扩展test列表 extend(self, iterable) iterable:传入可迭代对象(例如：传入列表，字符串等)
# test.extend([11, '22'])
# extend和append区别如下：
# test.extend([11, '22']) --> [11, 22, 33, 44, 55, 11, '22']
# test.extend('abcd') --> [11, 22, 33, 44, 55, 'a', 'b', 'c', 'd']
# test.append([11, '22']) --> [11, 22, 33, 44, 55, [11, '22']]
# test.append('abcd') --> [11, 22, 33, 44, 55, 'abcd']
# insert方法，在test列表指定位置插入元素
# insert(self, index, p_object) 参数：index：指定下标位置插入(下标前面插入) p_object:待插入元素
# test.insert(1, '551')
################################## List 列表之查找 ####################################
# index方法，查找元素索引位置(例如:test1 = [11,22,33,22] test.index(22)从左往右找到找到第一个22就停止后面的22就不找了)
# index(self, value, start=None, stop=None) 参数 vale:待查找下标的元素 start：从哪个下标开始查找 stop：寻找结束的下标(查找时不查找结束的下标)
# v = test.index(22, 0, 2) # --> 返回 1
################################## List 列表之其他 ####################################
# copy方法，浅拷贝test列表
# v = test.copy()
# count方法，计算test列表中指定元素出现的次数
# count(self, value) 参数：value：待计算的元素
# v1 = test.count(22)
# reverse方法，test列表反转
# test.reverse()
# sort方法，对test列表内元素进行排序
# sort(self, key=None, reverse=False)参数：reverse：False时从小到大排序，True时从大到小排序
# test.sort(reverse=True)
print(test)
######################################################################################################################################class list(object):
"""
list() -> new empty list
list(iterable) -> new list initialized from iterable's items
"""
def append(self, p_object): # real signature unknown; restored from __doc__
""" L.append(object) -- append object to end """
pass
def count(self, value): # real signature unknown; restored from __doc__
""" L.count(value) -> integer -- return number of occurrences of value """
return 0
def extend(self, iterable): # real signature unknown; restored from __doc__
""" L.extend(iterable) -- extend list by appending elements from the iterable """
pass
def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__
"""
L.index(value, [start, [stop]]) -> integer -- return first index of value.
Raises ValueError if the value is not present.
"""
return 0
def insert(self, index, p_object): # real signature unknown; restored from __doc__
""" L.insert(index, object) -- insert object before index """
pass
def pop(self, index=None): # real signature unknown; restored from __doc__
"""
L.pop([index]) -> item -- remove and return item at index (default last).
Raises IndexError if list is empty or index is out of range.
"""
pass
def remove(self, value): # real signature unknown; restored from __doc__
"""
L.remove(value) -- remove first occurrence of value.
Raises ValueError if the value is not present.
"""
pass
def reverse(self): # real signature unknown; restored from __doc__
""" L.reverse() -- reverse *IN PLACE* """
pass
def sort(self, cmp=None, key=None, reverse=False): # real signature unknown; restored from __doc__
"""
L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*;
cmp(x, y) -> -1, 0, 1
"""
pass
def __add__(self, y): # real signature unknown; restored from __doc__
""" x.__add__(y) <==> x+y """
pass
def __contains__(self, y): # real signature unknown; restored from __doc__
""" x.__contains__(y) <==> y in x """
pass
def __delitem__(self, y): # real signature unknown; restored from __doc__
""" x.__delitem__(y) <==> del x[y] """
pass
def __delslice__(self, i, j): # real signature unknown; restored from __doc__
"""
x.__delslice__(i, j) <==> del x[i:j]
Use of negative indices is not supported.
"""
pass
def __eq__(self, y): # real signature unknown; restored from __doc__
""" x.__eq__(y) <==> x==y """
pass
def __getattribute__(self, name): # real signature unknown; restored from __doc__
""" x.__getattribute__('name') <==> x.name """
pass
def __getitem__(self, y): # real signature unknown; restored from __doc__
""" x.__getitem__(y) <==> x[y] """
pass
def __getslice__(self, i, j): # real signature unknown; restored from __doc__
"""
x.__getslice__(i, j) <==> x[i:j]
Use of negative indices is not supported.
"""
pass
def __ge__(self, y): # real signature unknown; restored from __doc__
""" x.__ge__(y) <==> x>=y """
pass
def __gt__(self, y): # real signature unknown; restored from __doc__
""" x.__gt__(y) <==> x>y """
pass
def __iadd__(self, y): # real signature unknown; restored from __doc__
""" x.__iadd__(y) <==> x+=y """
pass
def __imul__(self, y): # real signature unknown; restored from __doc__
""" x.__imul__(y) <==> x*=y """
pass
def __init__(self, seq=()): # known special case of list.__init__
"""
list() -> new empty list
list(iterable) -> new list initialized from iterable's items
# (copied from class doc)
"""
pass
def __iter__(self): # real signature unknown; restored from __doc__
""" x.__iter__() <==> iter(x) """
pass
def __len__(self): # real signature unknown; restored from __doc__
""" x.__len__() <==> len(x) """
pass
def __le__(self, y): # real signature unknown; restored from __doc__
""" x.__le__(y) <==> x<=y """
pass
def __lt__(self, y): # real signature unknown; restored from __doc__
""" x.__lt__(y) <==> x<y """
pass
def __mul__(self, n): # real signature unknown; restored from __doc__
""" x.__mul__(n) <==> x*n """
pass
@staticmethod # known case of __new__
def __new__(S, *more): # real signature unknown; restored from __doc__
""" T.__new__(S, ...) -> a new object with type S, a subtype of T """
pass
def __ne__(self, y): # real signature unknown; restored from __doc__
""" x.__ne__(y) <==> x!=y """
pass
def __repr__(self): # real signature unknown; restored from __doc__
""" x.__repr__() <==> repr(x) """
pass
def __reversed__(self): # real signature unknown; restored from __doc__
""" L.__reversed__() -- return a reverse iterator over the list """
pass
def __rmul__(self, n): # real signature unknown; restored from __doc__
""" x.__rmul__(n) <==> n*x """
pass
def __setitem__(self, i, y): # real signature unknown; restored from __doc__
""" x.__setitem__(i, y) <==> x[i]=y """
pass
def __setslice__(self, i, j, y): # real signature unknown; restored from __doc__
"""
x.__setslice__(i, j, y) <==> x[i:j]=y
Use of negative indices is not supported.
"""
pass
def __sizeof__(self): # real signature unknown; restored from __doc__
""" L.__sizeof__() -- size of L in memory, in bytes """
pass
__hash__ = None
list举报
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