Do binary files contain more 1s or 0s? (coil.com)

"2 / 8 = 0.29"

0.25 according to my calculations

pictures and /dev/random should give 0.5, not 0.57, if not they are not properly compressed and it's not a proper random generation, which I don't really believe. Maybe similar error as what happened with the 0.29?

The mean byte value in decimal should be 127.5.

I guess it may be something about the hexadecimal -> decimal -> binary conversion -> count instances of '0' and '1' in string in the python code that is doing something wrong (it's also inefficient to roundtrip through decimal when the original bytes are already binary in the computer and to involve strings in this at all). Does it remove leading zeros perhaps?

    bin(decimal)[2:]

    bin(decimal)[2:].rjust(8, '0')

The code ignores leading zero bits in each byte, which is why it gets the surprising result of more ones than zeros.

Jesus this is some dumb shit.

In python, the string returned by

    bin(decimal)

drops the leading zeros

    >>> bin(3)
    '0b11'
    >>> bin(513)
    '0b1000000001'
    >>> bin(1024)
    '0b10000000000'

I don't want to turn this into a personal attack or an overly snarky comment but it's really something to try and implement a bit counting algo by hand and then fail to observe the way bin() behaves

The reason you're measuring more 1's than 0's is this line:

  binary = bin(decimal)[2:]

That's because while `bin(0xff)` is indeed "0b11111111", `bin(0x00)` is "0b0". Python omits your leading zeros.

A smaller nit, these lines:

  hexadecimal = binascii.hexlify(byte)
  decimal = int(hexadecimal, 16)

can be just

  decimal = byte[0]

There's a Linux application called "ent" that calculates the entropy of a file. I use it to see if it's worth it to compress a file before I ship it somewhere else.

It is of course vitally important that the 1's and the 0's even out, otherwise you might overflow the bit bucket and jam the tubes.

(This is actually a thing, encoding schemes like MFM and RLL in magnetic media ensure there aren't too many sequential 1 bits etc. See also "Grey codes")

> Consider a file which only contains the letter A. It has the following bits: 10000001

I thought A was 65, not 129?

I would assume < 0.5 on average since English strings are pretty common and the top bit is usually 0. Zero padding is fairly common in files too, while 1 padding is relatively rare.

There are at least two silly things in this code,

One is the hex conversion. Compare:

  >>> bin(int(binascii.hexlify(b"\x05"), 16))[2:]
  '101'

versus just:

  >>> bin(b"\x05"[0])[2:]
  '101'

Secondly, the code should just count the 1 bits; there is no need for a count of zeros.

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