Conversion between binary vector and 128 bit number

Question

Is there a way to convert back and forth between a binary vector and a 128-bit number? I have the following binary vector:

import numpy as np

bits = np.array([1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1,
                 0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0,
                 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 0,
                 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1,
                 0, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1,
                 1, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1], dtype=np.uint8)

which is a MD5 hash that I am trying use as a feature for a scikit-learn machine learning classifier (I need to represent the hash as a single feature).

Does this answer your question? [Convert binary (0|1) numpy to integer or binary-string?](https://stackoverflow.com/questions/41069825/convert-binary-01-numpy-to-integer-or-binary-string) — mozway, May 14 '22 at 14:09
@mozway I tried that solution but it only handle numbers up to 64 bits. — Kevin, May 14 '22 at 14:09
Maybe [this answer](https://stackoverflow.com/a/47515534/14923227) will work, but I am not sure how to convert the number back to a binary vector. — Kevin, May 14 '22 at 14:14
`numpy` (and `sklearn`) have a `int64` max integer size. floats can be larger. Python ints can also be longer, but can only be put in arrays as objects. — hpaulj, May 14 '22 at 15:09
@hpaulj I believe `sklearn` uses `float32` as its dtype according to their documentation: https://scikit-learn.org/stable/modules/generated/sklearn.ensemble.RandomForestClassifier.html#sklearn.ensemble.RandomForestClassifier.fit ? So if I try to use a `int64` or `float64` it will get truncated right? — Kevin, May 18 '22 at 18:37

score 0 · Answer 1 · answered May 14 '22 at 21:01

As commented above, numpy only goes up to 64bits, but python has variable length ints, so we can do 128bits int no problem.

The following will go from binary in np.array to python int back to binary in np.array.

import numpy as np

bits = np.array(
    [
        1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1,
        0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0,
        1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 0,
        1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1,
        0, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1,
        1, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1
    ],
    dtype=np.uint8
)

s = "".join(bits.astype("str"))  # move from array to string
n = int(s, 2)  # convert to int from string of base 2
print(n)

s = bin(n)[2:]  # get binary of int, cut "0b" prefix
np.array(list(s), dtype=np.uint8)  # put back in np.array

Conversion between binary vector and 128 bit number

1 Answers1