关于hashmap：Python中的哈希图

Hash Map in Python

我想在Python中实现HashMap。我想请用户输入。根据他的输入，我正在从HashMap中检索一些信息。如果用户输入HashMap的键，我想检索相应的值。

如何在Python中实现此功能？

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HashMap<String,String> streetno=new HashMap<String,String>();
streetno.put("1","Sachin Tendulkar");
streetno.put("2","Dravid");
streetno.put("3","Sehwag");
streetno.put("4","Laxman");
streetno.put("5","Kohli")

相关讨论

您想要的(在最初提出问题时)只是一个提示。提示：在Python中，您可以使用字典。

它是Python内置的。参见字典。

根据您的示例：

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streetno = {"1":"Sachine Tendulkar",
"2":"Dravid",
"3":"Sehwag",
"4":"Laxman",
"5":"Kohli" }

然后，您可以像这样访问它：

1	sachine = streetno["1"]

还值得一提：它可以使用任何非可变数据类型作为键。也就是说，它可以使用元组，布尔值或字符串作为键。

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streetno = { 1 :"Sachin Tendulkar",
2 :"Dravid",
3 :"Sehwag",
4 :"Laxman",
5 :"Kohli" }

并获取值：

1	name = streetno.get(3,"default value")

要么

1	name = streetno[3]

那就是使用数字作为键，在数字两边加上引号以使用字符串作为键。

哈希图是Python内置的，它们称为字典：

1 2	streetno = {} #create a dictionary called streetno streetno["1"] ="Sachin Tendulkar" #assign value to key"1"

用法：

1 2	"1" in streetno #check if key"1" is in streetno streetno["1"] #get the value from key"1"

请参阅文档以获取更多信息，例如内置方法等。它们很棒，并且在Python程序中非常常见(毫不奇怪)。

这是使用python的Hash Map的实现
为了简单起见，哈希映射的大小固定为16。
这可以轻松更改。
重新哈希不在此代码范围内。

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class Node:
def __init__(self, key, value):
self.key = key
self.value = value
self.next = None

class HashMap:
def __init__(self):
self.store = [None for _ in range(16)]
def get(self, key):
index = hash(key) & 15
if self.store[index] is None:
return None
n = self.store[index]
while True:
if n.key == key:
return n.value
else:
if n.next:
n = n.next
else:
return None
def put(self, key, value):
nd = Node(key, value)
index = hash(key) & 15
n = self.store[index]
if n is None:
self.store[index] = nd
else:
if n.key == key:
n.value = value
else:
while n.next:
if n.key == key:
n.value = value
return
else:
n = n.next
n.next = nd

hm = HashMap()
hm.put("1","sachin")
hm.put("2","sehwag")
hm.put("3","ganguly")
hm.put("4","srinath")
hm.put("5","kumble")
hm.put("6","dhoni")
hm.put("7","kohli")
hm.put("8","pandya")
hm.put("9","rohit")
hm.put("10","dhawan")
hm.put("11","shastri")
hm.put("12","manjarekar")
hm.put("13","gupta")
hm.put("14","agarkar")
hm.put("15","nehra")
hm.put("16","gawaskar")
hm.put("17","vengsarkar")
print(hm.get("1"))
print(hm.get("2"))
print(hm.get("3"))
print(hm.get("4"))
print(hm.get("5"))
print(hm.get("6"))
print(hm.get("7"))
print(hm.get("8"))
print(hm.get("9"))
print(hm.get("10"))
print(hm.get("11"))
print(hm.get("12"))
print(hm.get("13"))
print(hm.get("14"))
print(hm.get("15"))
print(hm.get("16"))
print(hm.get("17"))

输出：

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sachin
sehwag
ganguly
srinath
kumble
dhoni
kohli
pandya
rohit
dhawan
shastri
manjarekar
gupta
agarkar
nehra
gawaskar
vengsarkar

相关讨论

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class HashMap:
def __init__(self):
self.size = 64
self.map = [None] * self.size

def _get_hash(self, key):
hash = 0

for char in str(key):
hash += ord(char)
return hash % self.size

def add(self, key, value):
key_hash = self._get_hash(key)
key_value = [key, value]

if self.map[key_hash] is None:
self.map[key_hash] = list([key_value])
return True
else:
for pair in self.map[key_hash]:
if pair[0] == key:
pair[1] = value
return True
else:
self.map[key_hash].append(list([key_value]))
return True

def get(self, key):
key_hash = self._get_hash(key)
if self.map[key_hash] is not None:
for pair in self.map[key_hash]:
if pair[0] == key:
return pair[1]
return None

def delete(self, key):
key_hash = self._get_hash(key)

if self.map[key_hash] is None :
return False
for i in range(0, len(self.map[key_hash])):
if self.map[key_hash][i][0] == key:
self.map[key_hash].pop(i)
return True

def print(self):

print('---Phonebook---')
for item in self.map:
if item is not None:
print(str(item))

h = HashMap()

在这种情况下，Python Counter也是一个不错的选择：

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from collections import Counter

counter = Counter(["Sachin Tendulkar","Sachin Tendulkar","other things"])

print(counter)

这将返回一个字典，其中包含列表中每个元素的计数：

1	Counter({'Sachin Tendulkar': 2, 'other things': 1})