python中的二叉树模块内容:
BinaryTree:非平衡二叉树
AVLTree:平衡的AVL树
RBTree:平衡的红黑树
以上是用python写的,相面的模块是用c写的,并且可以做为Cython的包。
FastBinaryTree
FastAVLTree
FastRBTree
特别需要说明的是:树往往要比python内置的dict类慢一些,但是它中的所有数据都是按照某个关键词进行排序的,故在某些情况下是必须使用的。
安装和使用
安装方法
安装环境:
ubuntu12.04, python 2.7.6
安装方法
下载源码,地址:https://bitbucket.org/mozman/bintrees/src
进入源码目录,看到setup.py文件,在该目录内运行
python setup.py install
安装成功,ok!下面就看如何使用了。
应用
bintrees提供了丰富的API,涵盖了通常的多种应用。下面逐条说明其应用。
– 引用
如果按照一般模块的思路,输入下面的命令引入上述模块
>>> import bintrees
错了,这是错的,出现如下警告:(×××不可用,用×××)
Warning: FastBinaryTree not available, using Python version BinaryTree. Warning: FastAVLTree not available, using Python version AVLTree. Warning: FastRBTree not available, using Python version RBTree.
正确的引入方式是:
>>> from bintrees import BinaryTree #只引入了BinartTree >>> from bintrees import * #三个模块都引入了
– 实例化
看例子:
>>> btree = BinaryTree() >>> btree BinaryTree({}) >>> type(btree)
– 逐个增加键值对: .__setitem__(k,v) .复杂度O(log(n))(后续说明中,都会有复杂度标示,为了简单,直接标明:O(log(n)).)
看例子:
>>> btree.__setitem__(\"Tom\",\"headmaster\") >>> btree BinaryTree({\'Tom\': \'headmaster\'}) >>> btree.__setitem__(\"blog\",\"http://blog.csdn.net/qiwsir\") >>> btree BinaryTree({\'Tom\': \'headmaster\', \'blog\': \'http://blog.csdn.net/qiwsir\'})
– 批量添加: .update(E) E是dict/iterable,将E批量更新入btree. O(E*log(n))
看例子:
>>> adict = [(2,\"phone\"),(5,\"tea\"),(9,\"scree\"),(7,\"computer\")] >>> btree.update(adict) >>> btree BinaryTree({2: \'phone\', 5: \'tea\', 7: \'computer\', 9: \'scree\', \'Tom\': \'headmaster\', \'blog\': \'http://blog.csdn.net/qiwsir\'})
– 查找某个key是否存在: .__contains__(k) 如果含有键k,则返回True,否则返回False. O(log(n))
看例子:
>>> btree BinaryTree({2: \'phone\', 5: \'tea\', 7: \'computer\', 9: \'scree\', \'Tom\': \'headmaster\', \'blog\': \'http://blog.csdn.net/qiwsir\'}) >>> btree.__contains__(5) True >>> btree.__contains__(\"blog\") True >>> btree.__contains__(\"qiwsir\") False >>> btree.__contains__(1) False
– 根据key删除某个key-value: .__delitem__(key), O(log(n))
看例子:
>>> btree BinaryTree({2: \'phone\', 5: \'tea\', 7: \'computer\', 9: \'scree\', \'Tom\': \'headmaster\', \'blog\': \'http://blog.csdn.net/qiwsir\'}) >>> btree.__delitem__(5) #删除key=5的key-value,即:5:\'tea\' 被删除. >>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\', \'Tom\': \'headmaster\', \'blog\': \'http://blog.csdn.net/qiwsir\'})
– 根据key值得到该kye的value: .__getitem__(key)
看例子:
>>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\', \'Tom\': \'headmaster\', \'blog\': \'http://blog.csdn.net/qiwsir\'}) >>> btree.__getitem__(\"blog\") \'http://blog.csdn.net/qiwsir\' >>> btree.__getitem__(7) \'computer\' >>> btree._getitem__(5) #在btree中没有key=5,于是报错。 Traceback (most recent call last): File \"\", line 1, in AttributeError: \'BinaryTree\' object has no attribute \'_getitem__\'
– 迭代器: .__iter__()
看例子:
>>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\', \'Tom\': \'headmaster\', \'blog\': \'http://blog.csdn.net/qiwsir\'}) >>> aiter = btree.__iter__() >>> aiterat 0xb7416dec> >>> aiter.next() #注意:next()一个之后,该值从list中删除 2 >>> aiter.next() 7 >>> list(aiter) [9, \'Tom\', \'blog\'] >>> list(aiter) #结果是空 [] >>> bool(aiter) #but,is True True
– 树的数据长度: .__len__(),返回btree的长度。O(1)
看例子:
>>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\', \'Tom\': \'headmaster\', \'blog\': \'http://blog.csdn.net/qiwsir\'}) >>> btree.__len__() 5
– 找出key最大的k-v对: .__max__(),按照key排列,返回key最大的键值对。
– 找出key最小的键值对: .__min__()
看例子:
>>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\'}) >>> btree.__max__() (9, \'scree\') >>> btree.__min__() (2, \'phone\')
– 两棵树的关系运算
看例子:
>>> other = [(3,\'http://www.jb51.net\'),(7,\'qiwsir\')] >>> bother = BinaryTree() #再建一个树 >>> bother.update(other) #加入数据 >>> bother BinaryTree({3: \'http://www.jb51.net\', 7: \'qiwsir\'}) >>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\'}) >>> btree.__and__(bother) #重叠部分部分 BinaryTree({7: \'computer\'}) >>> btree.__or__(bother) #全部 BinaryTree({2: \'phone\', 3: \'http://www.jb51.net, 7: \'computer\', 9: \'scree\'}) >>> btree.__sub__(bother) #btree不与bother重叠的部分 BinaryTree({2: \'phone\', 9: \'scree\'}) >>> btree.__xor__(bother) #两者非重叠部分 BinaryTree({2: \'phone\', 3: \'http://www.jb51.net, 9: \'scree\'})
– 输出字符串模样,注意仅仅是输出的模样罢了: .__repr__()
看例子:
>>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\'}) >>> btree.__repr__() \"BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\'})\"
– 清空树中的所有数据 :.clear(),O(log(n))
看例子:
>>> bother BinaryTree({3: \'http://blog.csdn.net/qiwsir\', 7: \'qiwsir\'}) >>> bother.clear() >>> bother BinaryTree({}) >>> bool(bother) False
– 浅拷贝: .copy(),官方文档上说是浅拷贝,但是我做了操作实现,是下面所示,还不是很理解其“浅”的含义。O(n*log(n))
看例子:
>>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\'}) >>> ctree = btree.copy() >>> ctree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\'}) >>> btree.__setitem__(\"github\",\"qiwsir\") #增加btree的数据 >>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\', \'github\': \'qiwsir\'}) >>> ctree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\'}) #这是不是在说明属于深拷贝呢? >>> ctree.__delitem__(7) #删除ctree的一个数据 >>> ctree BinaryTree({2: \'phone\', 9: \'scree\'}) >>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\', \'github\': \'qiwsir\'})
– 移除树中的一个数据: .discard(key),这个功能与.__delitem__(key)类似.两者都不反悔值。O(log(n))
看例子:
>>> ctree BinaryTree({2: \'phone\', 9: \'scree\'}) >>> ctree.discard(2) #删除后,不返回值,或者返回None >>> ctree BinaryTree({9: \'scree\'}) >>> ctree.discard(2) #如果删除的key不存在,也返回None >>> ctree.discard(3) >>> ctree.__delitem__(3) #但是,.__delitem__(key)则不同,如果key不存在,会报错。 Traceback (most recent call last): File \"\", line 1, in File \"/usr/local/lib/python2.7/site-packages/bintrees/abctree.py\", line 264, in __delitem__ self.remove(key) File \"/usr/local/lib/python2.7/site-packages/bintrees/bintree.py\", line 124, in remove raise KeyError(str(key)) KeyError: \'3\'
– 根据key查找,并返回或返回备用值: .get(key[,d])。如果key在树中存在,则返回value,否则如果有d,则返回d值。O(log(n))
看例子:
>>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\', \'github\': \'qiwsir\'}) >>> btree.get(2,\"algorithm\") \'phone\' >>> btree.get(\"python\",\"algorithm\") #没有key=\'python\'的值,返回\'algorithm\' \'algorithm\' >>> btree.get(\"python\") #如果不指定第二个参数,若查不到,则返回None >>>
– 判断树是否为空: is_empty().根据树数据的长度,如果数据长度为0,则为空。O(1)
看例子:
>>> ctree BinaryTree({9: \'scree\'}) >>> ctree.clear() #清空数据 >>> ctree BinaryTree({}) >>> ctree.is_empty() True >>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\', \'github\': \'qiwsir\'}) >>> btree.is_empty() False
– 根据key、value循环从树中取值:
>>.items([reverse])–按照(key,value)结构取值;
>>.keys([reverse])–key
>>.values([reverse])–value. O(n)
>>.iter_items(s,e[,reverse]–s,e是key的范围,也就是生成在某个范围内的key的迭代器 O(n)
看例子:
>>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\', \'github\': \'qiwsir\'}) >>> for (k,v) in btree.items(): ... print k,v ... 2 phone 7 computer 9 scree github qiwsir >>> for k in btree.keys(): ... print k ... 2 7 9 github >>> for v in btree.values(): ... print v ... phone computer scree qiwsir >>> for (k,v) in btree.items(reverse=True): #反序 ... print k,v ... github qiwsir 9 scree 7 computer 2 phone >>> btree BinaryTree({2: \'phone\', 5: None, 7: \'computer\', 8: \'eight\', 9: \'scree\', \'github\': \'qiwsir\'}) >>> for (k,v) in btree.iter_items(6,9): #要求迭代6<=key<9的键值对数据 ... print k,v ... 7 computer 8 eight >>>
– 删除数据并返回该值:
>>.pop(key[,d]), 根据key删除树的数据,并返回该value,但是如果没有,并也指定了备选返回的d,则返回d,如果没有d,则报错;
>>.pop_item(),在树中随机选择(key,value)删除,并返回。
看例子:
>>> ctree = btree.copy() >>> ctree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\', \'github\': \'qiwsir\'}) >>> ctree.pop(2) #删除key=2的数据,返回其value \'phone\' >>> ctree.pop(2) #删除一个不存在的key,报错 Traceback (most recent call last): File \"\", line 1, in File \"/usr/local/lib/python2.7/site-packages/bintrees/abctree.py\", line 350, in pop value = self.get_value(key) File \"/usr/local/lib/python2.7/site-packages/bintrees/abctree.py\", line 557, in get_value raise KeyError(str(key)) KeyError: \'2\' >>> ctree.pop_item() #随机返回一个(key,value),并已删除之 (7, \'computer\') >>> ctree BinaryTree({9: \'scree\', \'github\': \'qiwsir\'}) >>> ctree.pop(7,\"sing\") #如果没有,可以返回指定值 \'sing\'
– 查找数据,并返回value: .set_default(key[,d]),在树的数据中查找key,如果存在,则返回该value。如果不存在,当指定了d,则将该(key,d)添加到树内;当不指定d的时候,添加(key,None). O(log(n))
看例子:
>>> btree BinaryTree({2: \'phone\', 7: \'computer\', 9: \'scree\', \'github\': \'qiwsir\'}) >>> btree.set_default(7) #存在则返回 \'computer\' >>> btree.set_default(8,\"eight\") #不存在,则返回后备指定值,并加入到树 \'eight\' >>> btree BinaryTree({2: \'phone\', 7: \'computer\', 8: \'eight\', 9: \'scree\', \'github\': \'qiwsir\'}) >>> btree.set_default(5) #如果不指定值,则会加入None >>> btree BinaryTree({2: \'phone\', 5: None, 7: \'computer\', 8: \'eight\', 9: \'scree\', \'github\': \'qiwsir\'}) >>> btree.get(2) #注意,.get(key)与.set_default(key[,d])的区别 \'phone\' >>> btree.get(3,\"mobile\") #不存在的 key,返回但不增加到树 \'mobile\' >>> btree BinaryTree({2: \'phone\', 7: \'computer\', 8: \'eight\', 9: \'scree\', \'github\': \'qiwsir\'})
– 根据key删除值
>>.remove(key),删除(key,value)
>>.remove_items(keys),keys是一个key组成的list,逐个删除树中的对应数据
看例子:
>>> ctree BinaryTree({2: \'phone\', 5: None, 7: \'computer\', 8: \'eight\', 9: \'scree\', \'github\': \'qiwsir\'}) >>> ctree.remove_items([5,6]) #key=6,不存在,报错 Traceback (most recent call last): File \"\", line 1, in File \"/usr/local/lib/python2.7/site-packages/bintrees/abctree.py\", line 271, in remove_items self.remove(key) File \"/usr/local/lib/python2.7/site-packages/bintrees/bintree.py\", line 124, in remove raise KeyError(str(key)) KeyError: \'6\' >>> ctree BinaryTree({2: \'phone\', 7: \'computer\', 8: \'eight\', 9: \'scree\', \'github\': \'qiwsir\'}) >>> ctree.remove_items([2,7,\'github\']) #按照 列表中顺序逐个删除 >>> ctree BinaryTree({8: \'eight\', 9: \'scree\'})
##以上只是入门的基本方法啦,还有更多内容,请移不到到文章开头的官方网站