写在前面
- 基于Python 3.7.2
- 环境：Anaconda 1.9.7
- 都是最基础的，有基础的忽略即可，下次写字符串
1. 元组
for method1 in dir(tuple):
if "_" not in method1:
print(method1)
count
index
1.1 count 计数
help(tuple.count)
Help on method_descriptor:
count(self, value, /)
Return number of occurrences of value.
- 返回出现的值的次数
t1=(1,2,3,4,1,2,3,1,2,1)
print(t1.count(1))
print(t1.count(5))
4
0
1.2 index
help(t1.index)
Help on built-in function index:
index(value, start=0, stop=9223372036854775807, /) method of builtins.tuple instance
Return first index of value.
Raises ValueError if the value is not present.
- 返回第一个匹配值的索引值
- 如果值不存在就抛出异常ValueError
- 默认的起始索引是0，结束索引是9223372036854775807（2的63次方-1）
t1=('a','b','c','d','a')
print(t1.index('a')) #打印第一个a的索引
print(t1.index('b'))
print(t1.index('e')) #e不存在抛出异常
0
1
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-5-bf7ccf31889f> in <module>
2 print(t1.index('a'))
3 print(t1.index('b'))
----> 4 print(t1.index('e'))
ValueError: tuple.index(x): x not in tuple
2. 集合
for method1 in dir(set):
if "_" not in method1:
print(method1)
add
clear
copy
difference
discard
intersection
isdisjoint
issubset
issuperset
pop
remove
union
update
2.1. add
help(set.add)
Help on method_descriptor:
add(...)
Add an element to a set.
This has no effect if the element is already present.
- 增加一个元素到一个集合中
- 如果元素已经存在没有效果（集合不可重复）
set1={1,2,3}
set1.add('a')
set1.add(4)
set1.add(1) #添加重复的元素无效
print(set1)
try:
set1.add([5,6]) #不可哈希的类型:list，不可以作为集合的元素
except TypeError:
print("unhashable type: 'list'")
set1.add((5,6))
print(set1)
try:
set1.add({7,8})
except TypeError:
print("unhashable type: 'set'")
try:
set1.add({'age':18})
except TypeError:
print("unhashable type: 'dict'")
{1, 2, 3, 4, 'a'}
unhashable type: 'list'
{1, 2, 3, 4, 'a', (5, 6)}
unhashable type: 'set'
unhashable type: 'dict'
总结：list、set、dict这些不可哈希（可变）的元素不可以作为set中的元素
2.2. clear
清空
help(set.clear)
Help on method_descriptor:
clear(...)
Remove all elements from this set.
set1={1,2,3}
set1.clear()
print(set1)
set()
2.3. copy
复制
help(set.copy)
set1={1,2,3}
set2=set1.copy()
print(set2)
{1, 2, 3}
2.4. difference 差集
等价于-（减法）
help(set.difference)
Help on method_descriptor:
difference(...)
Return the difference of two or more sets as a new set.
(i.e. all elements that are in this set but not the others.)
- 返回集合的不同
- 返回是一个集合
set1={1,2,3}
set2={3,4,5}
set3={2,6,7}
print(set1.difference(set2)) #在set1中，但不在set2中的
print(set1-set2) #减法，就是差集
print('*********')
print(set1.difference(set2,set3)) #在set1中，但不在set2和set3中
print(set1-set2-set3)
print(type(set1-set2)) #返回值是set
{1, 2}
{1, 2}
*********
{1}
{1}
<class 'set'>
set1={1,2,3}
set2={3,4,5}
print(set1-set2)
{1, 2}
2.5. discard 删除元素
help(set.discard)
Help on method_descriptor:
discard(...)
Remove an element from a set if it is a member.
If the element is not a member, do nothing.
- 移除一个成员
- 如果不是成员，啥也不做
set1={1,2,3}
set1.discard(1)
print(set1)
set1.discard(4)
print(set1)
{2, 3}
{2, 3}
2.6. intersection 交集
等价于&
help(set.intersection)
Help on method_descriptor:
intersection(...)
Return the intersection of two sets as a new set.
(i.e. all elements that are in both sets.)
- 返回交集（多个集合里面的公共部分）
set1={1,2,3}
set2={2,3,4}
print(set1.intersection(set2))
print(set1&set2) #还可以这么写
print(type(set1.intersection(set2)))
{2, 3}
{2, 3}
<class 'set'>
2.7. isdisjoint 是否有交集
help(set.isdisjoint)
Help on method_descriptor:
isdisjoint(...)
Return True if two sets have a null intersection.
- 如果2个集合没有交集就返回True
set1={1,2,3}
set2={3,4,5}
set3={4,5,6}
print(set1.isdisjoint(set2)) #有交集返回False
print(set1.isdisjoint(set3)) #无交集返回True
False
True
2.8. issubset 是否子集
等价于小于(<)
help(set.issubset)
Help on method_descriptor:
issubset(...)
Report whether another set contains this set.
set1={1,2}
set2={1,2,3}
set3={2,3,4}
print(set1.issubset(set2))
print(set1<set2) #等价写法
print(set1.issubset(set3))
True
True
False
2.9. issuperset 是否超集
等价于(>)
help(set.issuperset)
Help on method_descriptor:
issuperset(...)
Report whether this set contains another set.
set1={1,2,3}
set2={1,2}
set3={3,4}
print(set1.issuperset(set2))
print(set1>set2)
print(set1.issuperset(set3))
True
True
False
2.10. pop
help(set.pop)
Help on method_descriptor:
pop(...)
Remove and return an arbitrary set element.
Raises KeyError if the set is empty.
1. 删除并返回任意一个元素（无序的）
2. 如果set是空的就返回KeyError
set1={1,2}
set1.pop()
print(set1)
set1.pop()
set1.pop()
{2}
---------------------------------------------------------------------------
KeyError Traceback (most recent call last)
<ipython-input-38-dcf4d9ec963e> in <module>
3 print(set1)
4 set1.pop()
----> 5 set1.pop()
KeyError: 'pop from an empty set'
2.11. remove
help(set.remove)
Help on method_descriptor:
remove(...)
Remove an element from a set; it must be a member.
If the element is not a member, raise a KeyError.
1. 删除集合中的一个元素，必须是其中的元素
2. 如果不是集合的成员，抛出KeyError
set1={1,2,3}
set1.remove(1)
print(set1)
set1.remove(1)
{2, 3}
---------------------------------------------------------------------------
KeyError Traceback (most recent call last)
<ipython-input-39-71361082f76e> in <module>
2 set1.remove(1)
3 print(set1)
----> 4 set1.remove(1)
KeyError: 1
2.12. union
等价于|
help(set.union)
Help on method_descriptor:
union(...)
Return the union of sets as a new set.
(i.e. all elements that are in either set.)
1. 返回集合的联合(一个新的集合)
set1={1,2}
set2={2,3}
set3={4,5}
print(set1.union(set2))
print(set1|set3)
{1, 2, 3}
{1, 2, 4, 5}
2.13. update
help(set.update)
Help on method_descriptor:
update(...)
Update a set with the union of itself and others.
set1={1}
set1.update({2,3})
print("通过集合更新： ",set1)
set1.update('hoo')
print("通过字符串更新： ",set1)
set1.update([4,5])
print("通过列表更新： ",set1)
set1.update((6,7))
print("通过元组更新： ",set1)
set1.update({'age':18})
print("通过字典更新： ",set1,"值被忽略了")
try:
set1.update(1)
except TypeError:
print("通过数字更新: 'int' object is not iterable"+" 数字是不可迭代的对象")
通过集合更新： {1, 2, 3}
通过字符串更新： {1, 2, 3, 'o', 'h'}
通过列表更新： {1, 2, 3, 4, 5, 'o', 'h'}
通过元组更新： {1, 2, 3, 4, 5, 6, 7, 'o', 'h'}
通过字典更新： {1, 2, 3, 4, 5, 6, 7, 'age', 'o', 'h'} 值被忽略了
通过数字更新: 'int' object is not iterable 数字是不可迭代的对象
集合总结
十三个方法
- add 加元素
- clear 清空
- copy 复制
- difference 差集
- discard 删除元素
- intersectio 交集
- isdisjoint 是否有交集
- issubset 是否子集
- issuperset 是否超集
- pop 机弹出元素
- remove 弹出指定元素
- union 并集
- update 更新
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