Converting binary to decimal integer output

Question

You can use int and set the base to 2 (for binary):

>>> binary = raw_input('enter a number: ')
enter a number: 11001
>>> int(binary, 2)
25
>>>

---

However, if you cannot use int like that, then you could always do this:

binary = raw_input('enter a number: ')
decimal = 0
for digit in binary:
    decimal = decimal*2 + int(digit)
print decimal

Below is a demonstration:

>>> binary = raw_input('enter a number: ')
enter a number: 11001
>>> decimal = 0
>>> for digit in binary:
...     decimal = decimal*2 + int(digit)
...
>>> print decimal
25
>>>

Binary to Decimal

int(binaryString, 2)

Decimal to Binary

format(decimal ,"b")

There is actually a much faster alternative to convert binary numbers to decimal, based on artificial intelligence (linear regression) model:

1. Train an AI algorithm to convert 32-binary number to decimal based.
2. Predict a decimal representation from 32-binary.

See example and time comparison below:

from sklearn.linear_model import LinearRegression
from sklearn.model_selection import train_test_split
import numpy as np

y = np.random.randint(0, 2**32, size=10_000)

def gen_x(y):
    _x = bin(y)[2:]
    n = 32 - len(_x)
    return [int(sym) for sym in '0'*n + _x]

X = np.array([gen_x(x) for x in y])

model = LinearRegression()
model.fit(X, y)

def convert_bin_to_dec_ai(array):
    return model.predict(array)

y_pred = convert_bin_to_dec_ai(X)

Time comparison:

This AI solution converts numbers almost x10 times faster than conventional way!

If you want/need to do it without int:

sum(int(c) * (2 ** i) for i, c in enumerate(s[::-1]))

This reverses the string (s[::-1]), gets each character c and its index i (for i, c in enumerate(), multiplies the integer of the character (int(c)) by two to the power of the index (2 ** i) then adds them all together (sum()).