💡 Problem Formulation: When working with integers and binary operations in Python, a common necessity is to convert an integer into its corresponding binary representation, specifically into an array or list of bits. For example, converting the integer 9 into an array of bits would yield the array [1, 0, 0, 1], which represents the binary number 1001.
Method 1: Using bin() and List Comprehension
This method involves converting an integer to its binary string representation with bin() and then creating a bit array using list comprehension to extract each bit. It is both readable and concise.
Here’s an example:
integer = 9 # Convert to binary and remove the '0b' prefix binary_string = bin(integer)[2:] # Use list comprehension to create the bit array bit_array = [int(bit) for bit in binary_string] print(bit_array)
Output:
[1, 0, 0, 1]
This snippet first converts the integer 9 into its binary form ‘1001’ as a string. The [2:] slice removes the ‘0b’ prefix that Python includes to indicate a binary literal. Finally, it iterates through the string characters (‘1’, ‘0’, ‘0’, ‘1’), converting them to integers and composing the array of bits.
Method 2: Using format()
The format() method can format an integer as a binary string, which we can then convert to an array of bits. This method offers formatting options and is useful for specifying the number of bits.
Here’s an example:
integer = 9 # Format integer as a binary string with padding of zeros binary_string = format(integer, '08b') # Convert string into bit array bit_array = [int(bit) for bit in binary_string] print(bit_array)
Output:
[0, 0, 0, 0, 1, 0, 0, 1]
In this code snippet, format() is used to turn the integer 9 into an 8-bit binary string. The ’08b’ formatting string tells Python to represent the number in binary with at least 8 digits, padding with zeros if necessary. The resulting string is then converted into an array of bits using the same list comprehension strategy as in Method 1.
Method 3: Using Bit Shifting and Masking
Bit shifting and masking directly manipulate the integer’s bits to create an array without converting it to a binary string. This can be more efficient and is a common approach in low-level programming.
Here’s an example:
integer = 9 # Find the length of the binary representation bit_length = integer.bit_length() # Use bit shifting and masking to create the bit array bit_array = [(integer >> bit) & 1 for bit in range(bit_length-1, -1, -1)] print(bit_array)
Output:
[1, 0, 0, 1]
This code generates the bit array by shifting the integer right by each bit position in reverse and then applying a bitwise AND with 1 to isolate each bit. The bit_length() method is used to determine the number of bits to be considered, ensuring we don’t have leading zeros.
Method 4: Using the bitarray Library
If external libraries are an option, the bitarray library offers a dedicated method for converting integers to bit arrays. This method is especially powerful when dealing with a large number of bit manipulations.
Here’s an example:
from bitarray import bitarray integer = 9 # Use bitarray to create a bit array from integer bit_arr = bitarray() bit_arr.frombytes(integer.to_bytes((integer.bit_length() + 7) // 8, 'big')) print(bit_arr.tolist())
Output:
[1, 0, 0, 1]
Here, bitarray.frombytes() is used to create a bitarray object from the bytes representing our integer, which is converted to bytes using to_bytes(). The resulting bitarray object can be easily converted to a list of bits. Note that this method requires the installation of the bitarray library.
Bonus One-Liner Method 5: Using Bitwise Operations in a List Comprehension
For those who love concise code, here’s a one-liner that leverages bitwise operations and list comprehension without first converting the integer to a binary string.
Here’s an example:
integer = 9 # One-liner to get the bit array bit_array = [(integer >> i) & 1 for i in range(integer.bit_length())][::-1] print(bit_array)
Output:
[1, 0, 0, 1]
This one-liner combines bit shifting, masking, and a reversed range to produce the bit array directly. It is a compact and efficient way of achieving the conversion, but it may be less readable for those unfamiliar with bitwise operations. It is also worth noting that the array needs to be reversed at the end to get the correct bit order.
Summary/Discussion
- Method 1: Using
bin()and List Comprehension. Strengths: Readable and simple. Weaknesses: Unnecessary string manipulation if performance is critical. - Method 2: Using
format(). Strengths: Allows formatting and zero-padding. Weaknesses: Like Method 1, involves string manipulation. - Method 3: Bit Shifting and Masking. Strengths: Efficient and suitable for performance-critical applications. Weaknesses: Can be less readable for those not familiar with bitwise operations.
- Method 4: Using the bitarray Library. Strengths: Powerful for numerous bit manipulations. Weaknesses: Requires an external library, not built into standard Python.
- Bonus Method 5: One-Liner with Bitwise Operations. Strengths: Concise and efficient. Weaknesses: Potentially difficult to understand and less readable.