add bin_to_hexadecimal (TheAlgorithms#5156)

Author: franciscoperez2021

DIRECTORY.md

@@ -107,6 +107,7 @@
 ## Conversions
   * [Binary To Decimal](https://github.com/TheAlgorithms/Python/blob/master/conversions/binary_to_decimal.py)
   * [Binary To Octal](https://github.com/TheAlgorithms/Python/blob/master/conversions/binary_to_octal.py)
+  * [Binary To Hexadecimal](https://github.com/TheAlgorithms/Python/blob/master/conversions/binary_to_hexadecimal.py)
   * [Decimal To Any](https://github.com/TheAlgorithms/Python/blob/master/conversions/decimal_to_any.py)
   * [Decimal To Binary](https://github.com/TheAlgorithms/Python/blob/master/conversions/decimal_to_binary.py)
   * [Decimal To Binary Recursion](https://github.com/TheAlgorithms/Python/blob/master/conversions/decimal_to_binary_recursion.py)

conversions/binary_to_hexadecimal.py

@@ -0,0 +1,65 @@
+def bin_to_hexadecimal(binary_str: str) -> str:
+    """
+    Converting a binary string into hexadecimal using Grouping Method
+
+    >>> bin_to_hexadecimal('101011111')
+    '0x15f'
+    >>> bin_to_hexadecimal(' 1010   ')
+    '0x0a'
+    >>> bin_to_hexadecimal('-11101')
+    '-0x1d'
+    >>> bin_to_hexadecimal('a')
+    Traceback (most recent call last):
+    ...
+    ValueError: Non-binary value was passed to the function
+    >>> bin_to_hexadecimal('')
+    Traceback (most recent call last):
+    ...
+    ValueError: Empty string was passed to the function
+    """
+    BITS_TO_HEX = {
+        "0000": "0",
+        "0001": "1",
+        "0010": "2",
+        "0011": "3",
+        "0100": "4",
+        "0101": "5",
+        "0110": "6",
+        "0111": "7",
+        "1000": "8",
+        "1001": "9",
+        "1010": "a",
+        "1011": "b",
+        "1100": "c",
+        "1101": "d",
+        "1110": "e",
+        "1111": "f",
+    }
+
+    # Sanitising parameter
+    binary_str = str(binary_str).strip()
+
+    # Exceptions
+    if not binary_str:
+        raise ValueError("Empty string was passed to the function")
+    is_negative = binary_str[0] == "-"
+    binary_str = binary_str[1:] if is_negative else binary_str
+    if not all(char in "01" for char in binary_str):
+        raise ValueError("Non-binary value was passed to the function")
+
+    binary_str = (
+        "0" * (4 * (divmod(len(binary_str), 4)[0] + 1) - len(binary_str)) + binary_str
+    )
+
+    hexadecimal = []
+    for x in range(0, len(binary_str), 4):
+        hexadecimal.append(BITS_TO_HEX[binary_str[x : x + 4]])
+    hexadecimal_str = "0x" + "".join(hexadecimal)
+
+    return "-" + hexadecimal_str if is_negative else hexadecimal_str
+
+
+if __name__ == "__main__":
+    from doctest import testmod
+
+    testmod()