标签：数据类型 update com end 分享图片 内容 union 深浅copy add
当元组里面只有一个元素且没有逗号时，则该数据的数据类型与括号里面的元素相同。
tu1 = (‘laonanhai‘) tu2 = (‘laonanhai‘) print(tu1, type(tu1)) print(tu2, type(tu2),)
tu1 = (1) tu2 = (1,) print(tu1, type(tu1)) print(tu2, type(tu2))
tu1 = ([1, 2, 3]) tu2 = ([1, 2, 3],) print(tu1, type(tu1)) print(tu2, type(tu2))
在循环一个列表时，最好不要改变列表的大小，会影响你的最终结果。
li = [111, 222, 333, 444, 555,]，索引为奇数的所有元素全部删除。
方法一：
l1 = [111, 222, 333, 444, 555, ] del l1[1::2] print(l1)
方法二（错误展示）：
l1 = [111, 222, 333, 444, 555, ]
for index in range(len(l1)):
print(‘删除之前的index:%s‘ % index)
print(‘删除之前的l1:%s‘ % l1)
if index % 2 == 1:
del l1[index]
print(‘删除之后的index:%s‘ % index)
print(‘删除之后的l1:%s‘ % l1)
print(l1)
方法三（倒着删）：
l1 = [111, 222, 333, 444, 555, ]
for index in range(len(l1) - 1, -1, -1):
if index % 2 == 1:
del l1[index]
print(l1)
方法四（自己做的）：
l1 = [111, 222, 333, 444, 555, 666, 777, 888, 999, ]
i = len(l1)
count = 1
s = int(len(l1)/2)
for j in range(s):
del l1[count]
count += 1
print(l1)
dic = dict.fromkeys(‘abc‘, 666) print(dic)
dic = dict.fromkeys([11, 22, 33], 666) print(dic)
dic = dict.fromkeys([1, 2, 3], []) dic[1].append(666) print(dic)
错误示例：
dic = {‘k1‘: ‘v1‘, ‘k2‘: ‘v2‘, ‘k3‘: ‘v3‘, ‘name‘: ‘alex‘}
for i in dic:
if ‘k‘ in i:
del dic[i]
print(dic)
dic = {‘k1‘: ‘v1‘, ‘k2‘: ‘v2‘, ‘k3‘: ‘v3‘, ‘name‘: ‘alex‘}
l1 = []
for key in dic:
if ‘k‘ in key:
l1.append(key)
print(l1)
for key in l1:
del dic[key]
print(dic)
str ------> list：
split
list ----->str：
join
tuple ------> list：
tu1 = (1, 2, 3) l1 = list(tu1) print(l1)
list ------> tuple：
tu1 = (1, 2, 3) l1 = list(tu1) tu2 = tuple(l1) print(tu2)
dic ------> list：
list(dic) 列表中只有key。
dic = {‘k1‘: ‘v1‘, ‘k2‘: ‘v2‘,‘k3‘: ‘v3‘,}
l1 = list(dic)
print(l1)
print(list(dic.keys()))
print(list(dic.values()))
print(list(dic.items()))
0， ‘‘，[]， {}，() ------> bool都是False。
print(bool(0))
print(bool(‘‘))
print(bool(()))
print(bool([]))
print(bool({}))
print(bool([0, 0, 0]))
set1 = {1, 2, 3, ‘abc‘, (1, 2, 3), True, }
print(set1)
set2 = {11, 11, 11, 22}
print(set2)
列表的去重。
l1 = [11, 11, 22, 22, 33, 33, 33, 44] l2 = list(set(l1)) l2.sort() print(l2)
set1 = {‘alex‘, ‘WuSir‘, ‘RiTiAn‘, ‘egon‘, ‘barry‘}
set1.add(‘太白‘)
print(set1)
set1 = {‘alex‘, ‘WuSir‘, ‘RiTiAn‘, ‘egon‘, ‘barry‘}
set1.update(‘abc‘)
print(set1)
set1 = {‘alex‘, ‘WuSir‘, ‘RiTiAn‘, ‘egon‘, ‘barry‘}
set1.update([111, 2222, 333])
print(set1)
__.remove(‘A‘) 按元素删除。A为需要删除的内容。
set1 = {‘alex‘, ‘WuSir‘, ‘RiTiAn‘, ‘egon‘, ‘barry‘}
set1.remove(‘RiTiAn‘)
print(set1)
__.pop() 随机删除，有返回值。
set1 = {‘alex‘, ‘WuSir‘, ‘RiTiAn‘, ‘egon‘, ‘barry‘}
print(set1.pop())
print(set1)
__.clear() 清空集合。 空集合为set()。
set1 = {‘alex‘, ‘WuSir‘, ‘RiTiAn‘, ‘egon‘, ‘barry‘}
set1.clear()
print(set1)
del __ 删除集合。
set1 = {‘alex‘, ‘WuSir‘, ‘RiTiAn‘, ‘egon‘, ‘barry‘}
del set1
print(set1)
for循环。
set1 = {‘alex‘, ‘WuSir‘, ‘RiTiAn‘, ‘egon‘, ‘barry‘}
for i in set1:
print(i)
交集：__ & __ 或者 __.intersection(__)
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}
set3 = set1 & set2
print(set3)
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}
set3 = set1.intersection(set2)
print(set3)
并集：__ | __ 或者 __.union(__)
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}
set3 = set1 | set2
print(set3)
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}
set3 = set1.union(set2)
print(set3)
差集：__ - __ 或者 __.difference(__)
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}
set3 = set1 - set2
print(set3) # set1独有的
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}
set3 = set1.difference(set2) # set1独有的
print(set3)
反交集：__ ^ __ 或者 __.symmetric_difference(__)
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}
set3 = set1 ^ set2
print(set3)
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}
set3 = set1.symmetric_difference(set2)
print(set3)
子集：__ < __ 或者 __.issubset(__)
set1 = {1, 2, 3}
set2 = {1, 2, 3, 4, 5, 6}
print(set1 < set2) # True set1 是set2 的子集
set1 = {1, 2, 3}
set2 = {1, 2, 3, 4, 5, 6}
print(set1.issubset(set2)) # True set1是set2的子集
set1 = {1, 2, 3}
set2 = {1, 2, 3, 4, 5, 6}
print(set2 > set1) # set2 是 set1 的超集
set1 = {1, 2, 3}
set2 = {1, 2, 3, 4, 5, 6}
print(set2.issuperset(set1)) # set2 是 set1 的超集
frozenset（） frozenset是冻结的集合，它是不可变的，存在哈希值，好处是它可以作为字典的key，也可以作为其它集合的元素。缺点是一旦创建便不能更改，没有add，remove方法。
set1 = frozenset({1, 2, 3, ‘alex‘})
print(set1)
l1 = [1, 2, 3] l2 = l1 l3 = l2 l3.append(666) print(l1, l2, l3)
copy.（） 浅copy
l1 = [11, 22, 33] l2 = l1.copy() l1.append(666) print(l1, id(l1)) print(l2, id(l2))
当列表内层列表增加元素时，浅copy跟随变化。内层的列表同样是同一个地址。
对于浅copy来说，第一层创建的是新的内存地址，从第二层开始，指向的都是同一个内存地址，所以，对于第二层以及更深的层数来说，保持一致性。
l1 = [11, 22, [‘barry‘, [55, 66]], [11, 22]] l2 = l1.copy() l1[2].append(‘alex‘) print(l1, id(l1)) print(l2, id(l2)) print(l1, id(l1[-1])) print(l2, id(l2[-1]))
import copy
import copy l1 = [11, 22, 33] l2 = copy.deepcopy(l1) l1.append(666) print(l1, id(l1)) print(l2, id(l2))
import copy l1 = [11, 22, [‘barry‘]] l2 = copy.deepcopy(l1) l1[2].append(‘alex‘) print(l1, id(l1[-1])) print(l2, id(l2[-1]))
深copy 完全独立。
l1 = [1, 2, 3] l2 = [1, 2, 3] l1.append(666) print(l1, id(l1)) print(l2, id(l2))
对于切片来说，这是浅copy。
l1 = [1, 2, 3, 4, 5, 6, [11, 22]] l2 = l1[:] l1.append(666) print(l1, l2)
l1 = [1, 2, 3, 4, 5, 6, [11, 22]] l2 = l1[:] l1[-1].append(666) print(l1, l2)
Python全栈__数据类型的补充、集合set、深浅copy
标签：数据类型 update com end 分享图片 内容 union 深浅copy add
原文地址：https://www.cnblogs.com/ZN-225/p/9587953.html
