笨办法学习python之hashmap

#!/user/bin/env python
#-*-coding:utf-8 -*-
#Author: qinjiaxi
#初始化aMap列表，把列表num_buckets添加到aMap中，num_bukets用来存hashmap里设置的内容
def new(num_buckets = 256):
    """Initializes a map with the given number of buckets."""
    aMap = []
    for i in range(0, num_buckets):
        aMap.append([])
    return aMap
def hash_key(aMap, key):
    """Given a key this will create a number and then convert it to an index for the aMap's buckets."""
    return hash(key) % len(aMap)#利用求余(模除)来获得一个放置key的位置，其中hash()函数是用来获取一个数字或者字符串的哈希值(是一个整数)。
def get_bucket(aMap, key):
    """Given a key , find the bucket where it would go ."""
    bucket_id = hash_key(aMap, key)
    return  aMap[bucket_id]#通过bucket_id获取bucket
#使用enumerate()和for循环遍历bucket，用key获取索引、键、值
def get_slot(aMap, key, default = None):
    """
    Returns the index, key, and value of a slot found in a slot found in a bucket.
    Returns -1, key, and default(None if not set) when not found.
    """
    bucket = get_bucket(aMap, key)
    for i, kv in enumerate(bucket):
        k, v = kv
        if key == k:
            return i, k ,v
    return -1, key, default
#取值
def get(aMap, key ,default = None):
    """Gets the value in  a bucket for the given key, or the default."""
    i, k, v = get_slot(aMap, key, default = None)
    return v
#设置键值对追加到字典中，保证每个key存储一次
def set(aMap, key, value):
    """Set the key to the value, replacing any existing value."""
    bucket = get_bucket(aMap, key)
    i, k, v = get_slot(aMap, key)
#如果位置存在就代替
    if i >= 0:
        #the key exists, replace it
        bucket[i] = (key, value)
#不存在就追加到字典中
    else:
        #the key does not ,append to creat it
        bucket.append((key, value))
#通过key删除bucket
def delete(aMap, key):
    """ Deletes the given key from the Map."""
    bucket = get_bucket(aMap, key)
    for i in range(len(bucket)):
        k, v = bucket[i]
        if key == k:
            del bucket[i]
            break
#调试打印hashmap功能
def list(aMap):
    """Prints out what's in the Map"""
    for bucket in aMap:
        if bucket:
            for k,v in bucket:
                print (k, v)