Python 集合 set

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python set 集合

set 集合是一种数据类型

set跟list一样可以用{}来定义，但是pyton -v 版本 >2.7

set的数据格式：

s1={"abc","def"}      #{} 自己定义>>> print s1set(['abc', 'def'])  >>> s2=set("abcdef")  #set 函数用string进行初始化>>> print s2set(['a', 'c', 'b', 'e', 'd', 'f'])>>> s3=set(["abc",123,"def"])  #set 函数用list进行初始化>>> print s3set([123, 'abc', 'def'])

结合set的基本方法

 |  add(...)        #set 后面追加一个element |      Add an element to a set.   |       |      This has no effect if the element is already present. |   |  clear(...) |      Remove all elements from this set. |   |  copy(...) |      Return a shallow copy of a set. |   |  difference(...)   #s3.difference(s4)  #s3 跟s4 不同的element 组成一个新的set  |      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.) |   |  difference_update(...)     |      Remove all elements of another set from this set. |      >>> print s4set(['abc', 'def', 'ghk'])   >>> s3={"abc",123,"def"}>>> s3.difference(s4)  #之前的s3 s4 都不变，会把s3 中有，s4中没有的数据打印出来组成一个新的setset([123])>>> print s3set([123, 'abc', 'def'])>>> print s4set(['abc', 'def', 'ghk'])>>> s3.difference_update(s4)  #s3 直接是上面的结果，s4 不变化>>> print s3set([123])>>> print s4set(['abc', 'def', 'ghk']) |  discard(...) |      Remove an element from a set if it is a member. |       |      If the element is not a member, do nothing. |   |  intersection(...)  #交集 |      Return the intersection of two or more sets as a new set. |       |      (i.e. elements that are common to all of the sets.) |   |  intersection_update(...) |      Update a set with the intersection of itself and another. |   |  isdisjoint(...) |      Return True if two sets have a null intersection. |   |  issubset(...) |      Report whether another set contains this set. |   |  issuperset(...) |      Report whether this set contains another set. |   |  pop(...) |      Remove and return an arbitrary set element. |      Raises KeyError if the set is empty. |   |  remove(...) |      Remove an element from a set; it must be a member. |       |      If the element is not a member, raise a KeyError.

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