用Python编写B+树的插入操作

B+树插入操作需要考虑节点和平衡，如果是空树，按递增顺序将key插入叶子节点；如果不是空树，需要区分索引节点和叶子节点，不满足条件时还要对节点进行分解。

Python实现B+树插入操作

import math 1. 创建节点 class Node: def __init__(self, order): self.order = order self.values = [] self.keys = [] self.nextKey = None self.parent = None self.check_leaf = False def insert_at_leaf(self, leaf, value, key): if (self.values): temp1 = self.values for i in range(len(temp1)): if (value == temp1[i]): self.keys[i].append(key) break elif (value < temp1[i]): self.values = self.values[:i] + [value] + self.values[i:] self.keys = self.keys[:i] + [[key]] + self.keys[i:] break elif (i + 1 == len(temp1)): self.values.append(value) self.keys.append([key]) break else: self.values = [value] self.keys = [[key]] 1. B+树 class BplusTree: def __init__(self, order): self.root = Node(order) self.root.check_leaf = True 1. 插入操作 def insert(self, value, key): value = str(value) old_node = self.search(value) old_node.insert_at_leaf(old_node, value, key) if (len(old_node.values) == old_node.order): node1 = Node(old_node.order) node1.check_leaf = True node1.parent = old_node.parent mid = int(math.ceil(old_node.order / 2)) - 1 node1.values = old_node.values[mid + 1:] node1.keys = old_node.keys[mid + 1:] node1.nextKey = old_node.nextKey old_node.values = old_node.values[:mid + 1] old_node.keys = old_node.keys[:mid + 1] old_node.nextKey = node1 self.insert_in_parent(old_node, node1.values[0], node1) 1. 搜索操作 def search(self, value): current_node = self.root while(current_node.check_leaf == False): temp2 = current_node.values for i in range(len(temp2)): if (value == temp2[i]): current_node = current_node.keys[i + 1] break elif (value parentNode.order): parentdash = Node(parentNode.order) parentdash.parent = parentNode.parent mid = int(math.ceil(parentNode.order / 2)) - 1 parentdash.values = parentNode.values[mid + 1:] parentdash.keys = parentNode.keys[mid + 1:] value_ = parentNode.values[mid] if (mid == 0): parentNode.values = parentNode.values[:mid + 1] else: parentNode.values = parentNode.values[:mid] parentNode.keys = parentNode.keys[:mid + 1] for j in parentNode.keys: j.parent = parentNode for j in parentdash.keys: j.parent = parentdash self.insert_in_parent(parentNode, value_, parentdash) 1. 输出树 def printTree(tree): lst = [tree.root] level = [0] leaf = None flag = 0 lev_leaf = 0 node1 = Node(str(level[0]) + str(tree.root.values)) while (len(lst) != 0): x = lst.pop(0) lev = level.pop(0) if (x.check_leaf == False): for i, item in enumerate(x.keys): print(item.values) else: for i, item in enumerate(x.keys): print(item.values) if (flag == 0): lev_leaf = lev leaf = x flag = 1 record_len = 3 bplustree = BplusTree(record_len) bplustree.insert('5', '33') bplustree.insert('15', '21') bplustree.insert('25', '31') bplustree.insert('35', '41') bplustree.insert('45', '10') printTree(bplustree) if(bplustree.find('5', '34')): print("Found") else: print("Not found")登录后复制