How do I set my own custom mapping to my combinations iterator in python?

Question

I'm coding in python and I have an iterator that iterates through all the possible combinations of a 45 character string. I am generating them one at a time and I have found that it generates from the smallest possible combination which is 0000000..0000 to 0000000..0001. I want to set my own mapping to this so that it can generate from my own specified mapping. I want to do this by setting each value of the combinations to a number so I can set the smallest number to the first iteration.

My code is:

class MyIterator:

    def __init__(self, hex_string, repeat, mapping_function=None):
        self.hex_string = hex_string
        self.repeat = repeat
        self.mapping_function = mapping_function
        if self.mapping_function:
            self.hex_string = self.mapping_function(self.hex_string)
        self.combinations = itertools.product(self.hex_string, repeat=repeat)
        self.current = fastFunction(self.combinations, None)

    def __iter__(self):
        return self

    def modify_speed(self):
        pass

    def __next__(self):
        if self.current is not None:
            private_key = ''.join(self.current)
            self.current = fastFunction(self.combinations, None)
            return private_key
        else:
            raise StopIteration

def custom_mapping(hex_string):
   pass

iterator = MyIterator("0123456789abcdef", 45, mapping_function=custom_mapping)

for string in iterator:
    account = onlyFunction(string)
    # do something with the account

I want to set the custom mapping in the custom_mapping function. I want the mapping to map each character in the iterator variable to a number like 0,1,2 etc. that will allow the iterator to generate from whatever is set to 0 to the last character.

Answer 1

Here's the solution in my opinion.

def custom_mapping(hex_string):
    # Define the custom mapping here
    char_to_number = {
        '0': 3, '1': 1, '2': 4, '3': 2, '4': 0,
        '5': 5, '6': 6, '7': 7, '8': 8, '9': 9,
        'a': 10, 'b': 11, 'c': 12, 'd': 13, 'e': 14, 'f': 15
    }

    sorted_chars = sorted(hex_string, key=lambda char: char_to_number[char])
    return ''.join(sorted_chars)

• The custom_mapping function defines a dictionary char_to_number that maps each character to a number according to your custom order.
• It then sorts the characters in hex_string based on this custom order.
• By using the lambda function, we effectively tell the sorted() function to sort the characters according to the custom order defined in the char_to_number dictionary. Why i use the lambda function documentation