def __init__(self, size=16, alphaMax=0.5, alphaLowest=0.25):
self._size_ = size # size define the size of the hash table
self._hashTable_ = [[None, False] for i in range(self._size_)]
self._occupied_ = 0 # occupied will keep track of how many of nodes are utilized
self._alpha_ = self._occupied_ / self._size_
self._alphaMax_ = alphaMax
self._alphaLowest_ = alphaLowest
bitLength = self._size_.bit_length() + 1
if (bitLength < 16): bitLength = 16
self._prime1_ = generatePrimeNumber(bitLength)
self._uni_a1_ = randrange(1, self._prime1_ - 1)
self._uni_b1_ = randrange(0, self._prime1_ - 1)
self._prime2_ = generatePrimeNumber(bitLength)
self._uni_a2_ = randrange(0, self._prime2_ - 1)
self._uni_b2_ = randrange(0, self._prime2_ - 1)
def find(txt,pattern):
base = getBaseByString(txt)
#print("Base:",base)
size = len(pattern)
prime = generatePrimeNumber()
rtxt=RollingHash(base,prime)
rpat=RollingHash(base,prime)
# Get hash of the pattern
for i in range(size):
rpat.append(ord(pattern[i]))
# Get hash of the first (size) number of character string
for i in range(size):
rtxt.append(ord(txt[i]))
if(rtxt.hash == rpat.hash): # if the hashes matched confirm the match by comparing strings
if(txt[0:size] == pattern):
return 0
old=ord(txt[0]) # old is the first character of our sliding window that is to be remove
# Now we slide our window to the given txt
for i in range(size,len(txt)):
new = ord(txt[i]) # new is the next character that is to be added in the window
rtxt.append(new) # adding new in our hash
rtxt.skip(old) # remove old in our hash
old = ord(txt[i - size + 1]) # old character that will be deleted in next itteration
if(rtxt.hash == rpat.hash): # As the hashes matched confirm the match by comparing string characters
if(txt[i-size+1:i+1] == pattern):
return i - size +1
return -1
def __update__(self,updateFactor):
hashTableCopy = self._hashTable_ # updateFactor = 1/2 => reduce hashTable to half the size
self._size_ = int(self._size_*updateFactor) # updateFactor = 2 => extend hashTable to twice the size
self._hashTable_ = [LinkedList() for i in range(self._size_)]
# If you wanna use Numpy insted of list then
# Uncomment 2 lines below and comment the just above one
# self._hashTable_ = np.empty(self._size_,dtype=LinkedList)
# for i in range(self._size_): self._hashTable_[i] = LinkedList()
for i in range(self._size_): self._hashTable_[i] = LinkedList()
self._occupied_ = 0
self._alpha_ = self._occupied_ / self._size_
bitLength = self._size_.bit_length() + 1
self._prime_ = generatePrimeNumber(bitLength)
self._uni_a_ = randrange(0,self._prime_ - 1)
self._uni_b_ = randrange(0,self._prime_ - 1)
for ith_linkedList in hashTableCopy:
if(ith_linkedList.head == None):
continue
curr = ith_linkedList.head
while curr.next != None:
self.__add__(curr.key, curr.value)
curr = curr.next
self.__add__(curr.key, curr.value)
ith_linkedList.destroy()
def __update__(self, updateFactor):
hashTableCopy = self._hashTable_ # updateFactor = 1/2 => reduce hashTable to half the size
self._size_ = int(
self._size_ * updateFactor
) # updateFactor = 2 => extend hashTable to twice the size
self._hashTable_ = [[None, False] for i in range(self._size_)]
self._occupied_ = 0
self._alpha_ = self._occupied_ / self._size_
bitLength = self._size_.bit_length() + 1
bitLength = self._size_.bit_length() + 1
if (bitLength < 16): bitLength = 16
self._prime1_ = generatePrimeNumber(bitLength)
self._uni_a1_ = randrange(1, self._prime1_ - 1)
self._uni_b1_ = randrange(0, self._prime1_ - 1)
self._prime2_ = generatePrimeNumber(bitLength)
self._uni_a2_ = randrange(1, self._prime2_ - 1)
self._uni_b2_ = randrange(0, self._prime2_ - 1)
for node in hashTableCopy:
node = node[0]
if (node == None):
continue
self.__add__(node.key, node.value)
def __init__(self, size = 16, alphaMax = 0.5, alphaLowest = 0.25):
self._size_ = size # size define the size of the hash table
self._hashTable_ = [LinkedList() for i in range(self._size_)]
# If you wanna use Numpy insted of list then
# Uncomment 2 lines below and comment the just above one
# self._hashTable_ = np.empty(self._size_,dtype=LinkedList)
# for i in range(self._size_):self._hashTable_[i] = LinkedList()
self._occupied_ = 0 # occupied will keep track of how many of nodes are utilized
# alpha define the current utilization of hashTable
self._alpha_ = self._occupied_ / self._size_
# alphaMax define that when did the size of hashTable doubles 0.5 mean when the hashtable is filled 50% size of hashTable doubles
self._alphaMax_ = alphaMax
# alphaLowest define that when did the size of hashTable reduces to half
# 0.25 mean when the hashtable is left 25% of the size then size of hashTable reduces to half
self._alphaLowest_ = alphaLowest
# rand_a is used in multiplicationHash() is you wanna use multiplicationHash() insted of universalHashing() then uncomment it
# self.rand_a = randrange(self._size_//2,self._size_) | 1 # it's for multiplicationHash, | is just to confirm that rand_a is odd
# This is for Universal Hashes here our p can't exceed the word limit i.e. for a 64 bit architecture prime can't exceed 64 bit
bitLength = self._size_.bit_length() + 1
self._prime_ = generatePrimeNumber(bitLength) # primr is used by the hash function universalHashing()
self._uni_a_ = randrange(0,self._prime_ - 1) # uni_a and uni_b are used by the hash function universalHashing()
self._uni_b_ = randrange(0,self._prime_ - 1)
