adding a string into hash table

Question

Trying to add an insert(self, key) method that inserts the key into the appropriate position while linear probing for resolving collisions. My current code, I'm just not 100% sure how to inset the str into the hash table.

Testing code:

#Test
my_table  = HashTable(5)
my_table.insert('hello')
print("Hashtable:", my_table)

result:

Hashtable: [None, None, None, None, 'hello']

class HashTable:

    def __init__(self, capacity): 
        self.capacity = capacity 
        self.slots = [None] * self.capacity

    def __str__(self): 
        return str(self.slots )

    def is_empty(self): 
        return self.slots.count(None) == len(self.slots)

    def hash(self, key):
        sum = 0
        for char in key: 
            sum += ord(char) 
            sum2 = "%04d" % (sum) 
            digits = int((sum2[2]) + (sum2[3])) 
            number = int(digits * digits) 
        return number % len(self.slots)


    def insert(self, key): 
        count = 0 
        position = key%self.capacity 
        if self.slots[key%self.capacity] == None: 
            self.slots[key%self.capacity] = key 
        else: 
            while self.slots[position] != None: 
                position +=1 
                if position >= self.capacity: 
                    position = 0 
            self.slots[position%self.capacity] = key 
            return self.slots

Im currently getting a Type error

>>>TypeError: not all arguments converted during string formatting line 25, in insert
    position = key%self.capacity

I just need some advice on how to add the string into the hash table.

I added it into the error statement, its the line which says position = key % self.capactiy — M.Jones

falsetru falsetru · Accepted Answer · 2016-05-11T08:24:23

key ('hello') is a string object. You need to convert it to integer to do modulo. Otherwise it will perform printf-style string formatting; causes error because there's no % in the string:

position = key % self.capacity

Call self.hash to get hash value:

def insert(self, key): 
    position = self.hash(key) % self.capacity 
    if self.slots[position] == None: 
        self.slots[position] = key 
    else: 
        while self.slots[position] != None:
            position += 1
            if position >= self.capacity: 
                position = 0
        self.slots[position%self.capacity] = key
        return self.slots

UPDATE if body can be merged into else:

def insert(self, key): 
    position = self.hash(key) % self.capacity
    while self.slots[position] != None:
        position += 1
        if position >= self.capacity:
            position = 0
    self.slots[position%self.capacity] = key
    return self.slots

adding a string into hash table

1 Answers