I am trying to make a function that takes a string(key) and returns the slot number the hash table. Such that:
for key_word in ["John","Jane"]:
print(key_word, special_hash(key_word, 13))
>>> John 8
Jane 4
The function needs to convert each letter of the string to number form using alphabet position(eg. a=1, b= 2, c=3, etc). So the hash will be: John = 10+15+8+14= 47 -----> = 47 % tablesize(13)
You can convert the string to lowercase with lower function and iterate through the characters in the word, with a for loop, like this
def special_hash(word, tablesize):
for char in word.lower():
...
Then, you can get the character code corresponding to the character with ord function.
def special_hash(word, tablesize):
total_value = 0
for char in word.lower():
total_value += ord(char) - ord('a') + 1
Since we need to get the offset of the character in the alphabets, you can subtract the first value from the current value. Then finally, you can use modulo operator % to get the remainder of the division by tablesize
def special_hash(word, tablesize):
total_value = 0
for char in word.lower():
total_value += ord(char) - ord('a') + 1
return total_value % tablesize
The same can be written succintly with a generator expression and built-in sum function, like this
def special_hash(word, tablesize):
return sum(ord(char) - ord('a') + 1 for char in word.lower()) % tablesize
Use ord function and substract the ascii offset (a letter is 97 code, b is 98, and so on)
>>> ascii_offset = ord('a')-1 #http://www.asciitable.com/
>>> def special_hash(word, tablesize):
... return sum([ord(c) - ascii_offset for c in word.lower() ]) % tablesize
...
>>> special_hash('John',13)
8
>>> ##47%13 -> 8
tablesize?13.tablesizeis 13 only I guess