Split a large object into constant size list entries via list comprehension

Question

How to split a bytes object into a list/tuple of constant size objects? Ignore padding. Something like

max_size = 42
def foo(b: bytes):
    return [b[i:j] for (i, j) in range(max_size)]
foo(b'a' * 100000)

but working.

The 'list comprehension' part is only because it's concise, readable and efficient. IMHO a for() loop has been ugly for a decade or two.

Desired output: list[bytes objects of specific length]

What is your problem? Give a sample input and desired output — I'mahdi, Dec 29 '22 at 19:23
In the future, please start with your own research. If you just google "python" plus the question title, you get useful results. For more tips, see [ask]. — wjandrea, Dec 29 '22 at 19:46

score 1 · Accepted Answer · answered Dec 29 '22 at 19:41

I've provided a List comprehension and normal for loop solution.

sample_bytes = b'Some string encoded as bytes'
MAX_CHUNK_SIZE = 2

# personally I find this much more readable than list comprehension
def chunk_bytes_with_for_loop(b: bytes):
    for index in range(0, len(b), MAX_CHUNK_SIZE):
        yield b[index:index + MAX_CHUNK_SIZE] 

def chunk_bytes_with_list_comprehension(b: bytes):
    return [b[index * MAX_CHUNK_SIZE:(index + 1) * MAX_CHUNK_SIZE] for index in range((len(b) + MAX_CHUNK_SIZE - 1) // MAX_CHUNK_SIZE )]
    
print(list(chunk_bytes_with_for_loop(sample_bytes)))
print(chunk_bytes_with_list_comprehension(sample_bytes))

Split a large object into constant size list entries via list comprehension

1 Answers1