Adventures in Machine Learning

Mastering Bit Manipulation in Python: A Comprehensive Guide

Python is a powerful programming language that provides developers with the necessary tools to manipulate data through a variety of operations. Among these operations is bit manipulation, a technique that allows users to manipulate the binary code of data.

In this article, we will explore the different aspects of bit manipulation in Python, including bit masking and bitwise operations.

Understanding Bit Manipulation

Bit manipulation is the process of changing the value of a binary number by performing arithmetic operations on its individual bits. In Python, this is done by shifting or flipping the bits of the binary code in question.

Arithmetic operations such as addition, subtraction, multiplication, and division can be carried out on the individual bits of a binary number. Furthermore, bitwise operations such as AND, OR, XOR, and NOT can also be used to change the value of the binary number.

Introducing Bit Masking

In bit manipulation, a bit mask is a pattern used to set, unset or flip selected bits within a value. In Python, this is done through bitwise operations.

A bit mask is used to manipulate values by performing AND, OR, XOR, and NOT operations on a subset of the bits of a binary number. Bit masking is particularly useful in situations where you only need to modify specific bits of a binary number and leave others unaffected.

This technique can also be used to extract subsets from a larger binary sequence.

Python Bitwise Operators

In Python, there are six primitive bitwise operators: AND, OR, XOR, NOT, LEFT-SHIFT, and RIGHT-SHIFT. The AND operator (&) compares each bit of two numbers and generates a new number where each bit is set to 1 if the corresponding bits of both numbers are also 1; otherwise, the bit is set to 0.

The OR operator (|) compares each bit of two numbers and generates a new number where each bit is set to 1 if either one of the corresponding bits of both numbers is 1. Otherwise, the bit is set to 0.

The XOR operator (^), also known as the exclusive OR operator, compares each bit of two numbers and generates a new number where each bit is set to 1 only if the corresponding bits of both numbers are different. Otherwise, the bit is set to 0.

The NOT operator (~) is a unary operator that inverts the bits of a number. In other words, it changes every 0 to a 1 and every 1 to a 0.

The LEFT-SHIFT operator (<<) shifts the bits of the binary number to the left, effectively doubling the value of the number. For example, 8 << 2 would shift the bits of the binary number 1000 two positions to the left to produce the binary number 100000, which is equivalent to the decimal number 32.

The RIGHT-SHIFT operator (>>) shifts the bits of the binary number to the right, effectively halving the value of the number while discarding any remainders. For example, 8 >> 2 would shift the bits of the binary number 1000 two positions to the right to produce the binary number 10, which is equivalent to the decimal number 2.

Python AND Operator

The AND operator is a primitive bitwise operator in Python (&) that compares each bit in two numbers. If both bits are 1, the output is 1.

Otherwise, the output is 0. For example:

a = 10 # 1010 in binary

b = 6 # 0110 in binary

c = a & b # 0010 in binary

In this case, the AND operator compares the binary digits of a(1010) and b(0110), resulting in the binary output 0010.

This output in binary is equal to decimal number 2 (0010 -> 2), so the variable c will store the value of 2. Another example of Python code using the AND operator would be:

a = True

b = False

c = a & b

In this case, the output of the AND operator is False as one of the bits is zero.

Conclusion

In conclusion, bit manipulation provides a powerful set of tools for developers to manipulate binary code in Python. Bit masking and bitwise operations are two of the most common techniques used to perform bit manipulation.

Though each of the operators has its use, the AND operator is vital for comparing individual bits in two numbers and creating new values based on the logical operation. With that knowledge, developers can streamline their code to accomplish complex tasks while minimizing the resources used.

With the continued development of technology and the use of remote work, the knowledge of these techniques becomes increasingly essential, making them valuable skills for developers to learn.

3) Python OR Operator

Python provides a set of bitwise operators to allow developers to manipulate binary data. One of these operators is the OR operator, represented by the character `|`.

The OR operator is a logical operator, meaning that it evaluates multiple conditions and returns a true/false result. How OR operator works:

The OR operator performs an “inclusive or” operation on the individual bits of two integer values.

For each bit position in the binary representation of the operands, if either bit is 1, then the result bit in that position is also 1; otherwise, it is 0. For example, if we apply the OR operator to the integers 3 and 6, we obtain:

3 | 6 = 7

In binary form, 3 is 0011, 6 is 0110, and 7 is 0111.

The OR operator takes each corresponding bit and applies the rule above to produce the result. So, the rightmost bit of 3 and of 6 is 1, resulting in 1 being stored in the rightmost bit of 7.

Similarly, the second rightmost bit of 3 is 1, resulting in 1 being stored in the second rightmost bit of 7. However, the second rightmost bit of 6 is 0, so we store a 0 in the second rightmost bit of 7.

Example of using OR operator:

We can use the OR operator in Python to find if a number is divisible by a given value. For example, we can check if a number is divisible by 3 or 5 using the OR operator as follows:

“`

n = 10

if n % 3 == 0 or n % 5 == 0:

print(“The number is divisible by 3 or 5”)

else:

print(“The number is not divisible by 3 or 5”)

“`

In this case, we check if the number `n` is divisible by 3 or 5 by using the OR operator.

If either one of the conditions is true, the if statement will evaluate to true and will print out “The number is divisible by 3 or 5”. Otherwise, it will print out “The number is not divisible by 3 or 5”.

4) Python NOT Operator

Python provides a logical operator called NOT, which is used to negate the truth value of an expression. The NOT operator is represented by the keyword `not`.

It can be used to test if a condition is false, and to invert the truth value of an expression. How NOT operator works:

The NOT operator works by inverting the truth value of a Boolean expression.

A Boolean expression is an expression that can be either true or false. If the expression is true, the NOT operator will return false.

If the expression is false, the NOT operator will return true. It’s worth noting that the NOT operator is not limited to Boolean expressions.

It can also be used to negate the bits of an integer value. This is known as the “complement of 2’s”.

When we use the NOT operator on an integer value, it negates each bit, effectively “flipping” the ones and zeroes. Example of using NOT operator:

We can use the NOT operator to test if a condition is false.

For example:

“`

is_raining = False

if not is_raining:

print(“It is not raining”)

else:

print(“It is raining”)

“`

In this case, we use the NOT operator to test if the `is_raining` variable is false. Since its value is false, the NOT operator will flip it into true, and the if statement will execute the first block of code, printing “It is not raining”.

Alternatively, we can use the NOT operator to negate the bits of an integer value. For example:

“`

a = 10 # 1010 in binary

b = ~a # 0101 in binary

print(b)

“`

In this case, we use the NOT operator to negate the bits of the integer value `a`. Since `a` is equal to 10, which is represented in binary form as `1010`, the NOT operation will convert it to `0101`, which is equal to 5 in decimal form.

The result will print out 5.

Conclusion:

In conclusion, Python provides a set of powerful bitwise operators that enable developers to manipulate binary data. The OR operator is used to perform an “inclusive or” operation on the individual bits of two integer values.

The NOT operator is used to negate the truth value of a Boolean expression, and also to invert the bits of an integer value. These operators can be used to simplify complex operations and can help developers save time and resources.

5) Python XOR Operator

Python provides a set of bitwise operators that enable developers to manipulate binary data. One of these operators is the XOR operator, represented by the character `^`.

The XOR operator is used to perform a bitwise exclusive or operation between two integers. How XOR operator works:

The XOR operator compares two integers by looking at each corresponding bit and applying the following rule: if the bits in the same position are identical, the corresponding result bit is 0; if the bits are different, the corresponding result bit is 1.

For example, if we apply the XOR operator to the integers 3 and 6, we obtain:

3 ^ 6 = 5

In binary form, 3 is 0011, 6 is 0110, and 5 is 0101. The XOR operator takes each corresponding bit and applies the rule above to produce the result.

So, the rightmost bit in 3 and 6 is different, resulting in 1 being stored in the rightmost bit of 5. Similarly, the second rightmost bit in 3 and 6 is identical, resulting in 0 being stored in the second rightmost bit of 5.

Conversely, the third and leftmost bits of 3 and 6 are different, resulting in 1 being stored in the third and leftmost bit of 5. Example of using XOR operator:

We can use the XOR operator in Python to add or remove specific permissions from a set of permissions.

For example, let’s say we have a binary number that represents a set of permissions, and we want to add or remove the “write” permission. We can achieve this using the XOR operator as follows:

“`

permissions = 0b0110

write_permission = 0b0010

# Add write permission

permissions |= write_permission

# Remove write permission

permissions ^= write_permission

“`

In this example, we have a binary number `permissions` that represents a set of permissions.

We want to add or remove the “write” permission represented by `write_permission` using the XOR operator. To add the permission, we perform a bitwise OR operation between `permissions` and `write_permission`.

To remove the permission, we perform a bitwise XOR operation between `permissions` and `write_permission`.

6) Python LEFT-SHIFT Operator

Python provides a set of bitwise operators that enable developers to manipulate binary data. One of these operators is the LEFT-SHIFT operator, represented by the characters `<<`.

The LEFT-SHIFT operator is used to shift the bits of a number to the left by a specified number of positions. How LEFT-SHIFT operator works:

The LEFT-SHIFT operator takes a binary equivalent of a decimal number and shifts it a certain number of positions to the left.

For example, if we shift the number 3 two positions to the left, we obtain:

3 << 2 = 12

In binary form, 3 is 0011 and 12 is 1100. The LEFT-SHIFT operator takes each bit in the binary representation of 3 and shifts it two positions to the left to produce the binary number 1100, which is equal to the decimal number 12.

Example of using LEFT-SHIFT operator:

We can use the LEFT-SHIFT operator in Python to perform fast multiplication or division by powers of 2. For example, let’s say we want to multiply a number by 8, which is equivalent to shifting the number three positions to the left.

We can achieve this using the LEFT-SHIFT operator as follows:

“`

n = 5

result = n << 3

“`

In this example, we have the number `n` equal to 5, and we want to multiply it by 8. We achieve this by shifting the bits of `n` three positions to the left using the LEFT-SHIFT operator, which produces the result of 40.

We can also use the LEFT-SHIFT operator in combination with the RIGHT-SHIFT operator to divide a number by a power of 2. For example:

“`

n = 20

result = n >> 2

“`

In this example, we have the number `n` equal to 20, and we want to divide it by 4, which is equivalent to shifting the bits to the right by two positions.

We achieve this by shifting the bits of `n` two positions to the right using the RIGHT-SHIFT operator, which produces the result of 5.

Conclusion:

In conclusion, Python provides a set of powerful bitwise operators that enable developers to manipulate binary data. The XOR operator is used to perform a bitwise exclusive or operation between two integers while the LEFT-SHIFT operator is used to shift the bits of a number to the left by a specified number of positions.

These operators can be used to speed up calculations and work with binary data more efficiently.

7) Python RIGHT-SHIFT Operator

Python provides a set of bitwise operators that enable developers to manipulate binary data. One of these operators is the RIGHT-SHIFT operator, represented by the characters `>>`.

The RIGHT-SHIFT operator is used to shift the bits of a number to the right by a specified number of positions. How RIGHT-SHIFT operator works:

The RIGHT-SHIFT operator takes a binary equivalent of a decimal number and shifts it a certain number of positions to the right.

For example, if we shift the number 12 two positions to the right, we obtain:

12 >> 2 = 3

In binary form, 12 is 1100 and 3 is 0011. The RIGHT-SHIFT operator takes each bit in the binary representation of 12 and shifts it two positions to the right to produce the binary number 0011, which is equal to the decimal number 3.

Example of using RIGHT-SHIFT operator:

We can use the RIGHT-SHIFT operator in Python to perform fast division or multiplication by powers of 2. For example, let’s say we want to divide a number by 8, which is equivalent to shifting the number three positions to the right.

We can achieve this using the RIGHT-SHIFT operator as follows:

“`

n = 40

result = n >> 3

“`

In this example, we have the number `n` equal to 40, and we want to divide it by 8. We achieve this by shifting the bits of `n` three positions to the right using the RIGHT-SHIFT operator, which produces the result of 5.

We can also use the RIGHT-SHIFT operator in combination with the LEFT-SHIFT operator to implement divide-by-power-of-2 and modulo-by-power-of-2 operations. For example:

“`

# Divide n by 4

result = (n >> 2)

# Modulo n by 4

result = (n & 0b11)

“`

In the first example, we shift the bits of `n` two positions to the right using the RIGHT-SHIFT operator to

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