Hash table implementation updated

Data Structures - Hashtables/Hash Table Implementation.py

@@ -1,42 +1,67 @@
-from random import randint
-class Hashtable():
-  def __init__(self):
-    self.mydict = ['None']*50
-    self.addr_list = []
-
-  def __str__(self):
-    return str(self.__dict__)
+class Hashtable:
+	def __init__(self):
+		"""
+		Create an array(self.mydict) with a bucket size - which is derived from the load factor.
+		The Load factor is a measure that decides when to increase the HashMap capacity to maintain the get() and put() operation complexity of O(1).
+		The default load factor of HashMap is 0.75f (75% of the map size).
+		Load Factor = (n/k)
+		where n is the number of max number of elements that can be stored dict
+		k is the bucket size
+		Optimal Load factor is around (2/3) such that the effect of hash collisions is minimum 
+		"""
+		self.bucket = 16
+		self.hashmap = [[] for i in range(self.bucket)]
+
+	def __str__(self):
+		return str(self.__dict__)
 
-  def _hash(self):
-    while True:
-      x = randint(0,49)
-      if x not in self.addr_list:
-        return x
-
-  def set(self,key,value):
-    address = self._hash()
-    self.mydict[address] = [key,value]
-    self.addr_list.append(address)
-
-  def get(self,key):
-
-    for i in self.addr_list:
-      if self.mydict[i][0] == key:
-        return self.mydict[i][1]    
-
-  def keys(self):
-    key_arr=[]
-    for i in self.addr_list:
-      key_arr.append(self.mydict[i][0])
-    return key_arr
+	def hash(self, key):
+		return len(key) % self.bucket
+
+	def put(self, key, value):
+		"""
+		value may already be present
+		"""
+		hash_value = self.hash(key)
+		reference = self.hashmap[hash_value]
+		for i in range(len(reference)):
+			if reference[i][0] == key:
+				reference[i][1] = value
+				return None
+		reference.append([key, value])
+		return None
+
+	def get(self, key):
+		"""
+		Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key
+		"""
+		hash_value = self.hash(key)
+		reference = self.hashmap[hash_value]
+		for i in range(len(reference)):
+			if reference[i][0] == key:
+				return reference[i][1]
+		return -1
+
+	def remove(self, key):
+		"""
+		Removes the mapping of the specified value key if this map contains a mapping for the key
+		"""
+		hash_value = self.hash(key)
+		reference = self.hashmap[hash_value]
+		for i in range(len(reference)):
+			if reference[i][0] == key:
+				reference.pop(i)
+				return None
+		return None
 
 h=Hashtable()
-h.set('grapes',1000)
-h.set('apples',10)
-h.set('oranges',300)
-h.set('bananas',200)
-x=h.get('grapes')
-key_arr = h.keys()
+h.put('grapes',1000)
+h.put('apples',10)
+h.put('ora',300)
+h.put('banan',200)
+print(h.get('grapes'))
+print(h)
+h.remove('apples')
 print(h)
-print(x)
-print(key_arr)
+
+