Created
January 1, 2018 08:03
-
-
Save sachinnair90/d2f720ff88f48dd4c057e6ced9d48913 to your computer and use it in GitHub Desktop.
Simple Hash table implementation in Python
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
class MyHashTable: | |
def __init__(self): | |
self.size = 11 | |
self.positions = [None] * self.size | |
self.values = [None] * self.size | |
def put(self,key,value): | |
hashvalue = self.hashfn(key,len(self.positions)) | |
if self.positions[hashvalue] == None: | |
self.positions[hashvalue] = key | |
self.values[hashvalue] = value | |
else: | |
if self.positions[hashvalue] == key: | |
self.values[hashvalue] = value #replace | |
else: | |
nextposition = self.rehash(hashvalue,len(self.positions)) | |
while self.positions[nextposition] != None and \ | |
self.positions[nextposition] != key: | |
nextposition = self.rehash(nextposition,len(self.positions)) | |
if self.positions[nextposition] == None: | |
self.positions[nextposition]=key | |
self.values[nextposition]=value | |
else: | |
self.values[nextposition] = value #replace | |
def hashfn(self,key,size): | |
return key%size | |
def rehash(self,oldhash,size): | |
return (oldhash+1)%size | |
def get(self,key): | |
startposition = self.hashfn(key,len(self.positions)) | |
value = None | |
stop = False | |
found = False | |
position = startposition | |
while self.positions[position] != None and \ | |
not found and not stop: | |
if self.positions[position] == key: | |
found = True | |
value = self.values[position] | |
else: | |
position=self.rehash(position,len(self.positions)) | |
if position == startposition: | |
stop = True | |
return value | |
def __getitem__(self,key): | |
return self.get(key) | |
def __setitem__(self,key,value): | |
self.put(key,value) | |
H = MyHashTable() | |
H[31]="cow" | |
H[44]="goat" | |
H[54]="cat" | |
H[17]="tiger" | |
H[77]="bird" | |
H[55]="pig" | |
H[20]="chicken" | |
H[26]="dog" | |
H[93]="lion" | |
print(H.positions) | |
print(H.values) | |
print(H[20]) | |
print(H[17]) | |
H[20]='duck' | |
print(H[20]) | |
print(H[99]) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment