How to Convert Byte Array back into string?

Question

I am writing a Huffman Coding program. So far I have only written the compression part: as expected it takes the text I want to compress, creates a code for each character and replaces each character with its respective code. This is my compressed text in a string format - I convert this string into a byte array using the following code:

def make_byte_array(self, padded_text):

        byte_array = bytearray()
        for i in range(0, len(padded_text), 8):
            byte_array.append(int(padded_text[i:i + 8], 2))
        
        return byte_array

I then save the byte_array into a .bin file by doing bytes(byte_array). I want to now be able to open this binary file, read the byte_array inside and turn it back into the string format of my compressed text in order to be able to decompress it. The problem is whenever I open and read this binary file, I get something like this:

b'\xad"\xfdK\xa8w\xc1\xec\xcb\xe5)\x1f\x1f\x92'

How would I go about converting this back into the string format of my compressed text?

Mark Adler · Accepted Answer · 2022-01-28 17:48:27Z

1

If s is that byte string:

for x in s:
    print(f'{x:08b}')

Instead of print, you can do what you like with the strings of 0's and 1's.

It is unnecessarily inefficient to go through strings of 0 and 1 characters for encoding and decoding. You should instead assemble and disassemble the bytes directly using the bit operators (<<, >>, |, &).

answered Jan 28, 2022 at 17:48

Mark Adler

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4 Comments

ajox3412 Over a year ago

Thank you! Silly question but how would the bit operators help me disassemble the bytes? Aren't they just AND and OR gates, and left and right shifts?

Mark Adler Over a year ago

Yes, and that's all you need. Shift down by k bits, & with 1, and the result is the bit from position k.

ajox3412 Over a year ago

Thanks again! One more thing - what does f'{x:08b}' mean exactly? What does the f'' do and does the 08b just split it into bits?

Mark Adler Over a year ago

Isn't that what google is for? f means a formatted string. The thing in braces says to print the integer x in binary (the b). The 8 says to print up to 8 digits. The 0 says to always print eight digits, including leading zeros.

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