Compound Operators

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What are Compound Operators?

A compound operator is a shortcut for performing an operation and assignment in one step.

Instead of writing:

x = x + 5

You can use a compound operator:

x += 5

These are very handy in loops, data preprocessing, training steps in machine learning, and working with counters.

Syntax Overview

Operator	Meaning	Equivalent to
+=	Add and assign	x = x + y
-=	Subtract and assign	x = x - y
*=	Multiply and assign	x = x * y
/=	Divide and assign	x = x / y
//=	Floor divide and assign	x = x // y
%=	Modulo and assign	x = x % y
**=	Power and assign	x = x ** y
&=	Bitwise AND and assign	x = x & y
`	=`	Bitwise OR and assign
^=	Bitwise XOR and assign	x = x ^ y
>>=	Bitwise right shift	x = x >> y
<<=	Bitwise left shift	x = x << y

Step-by-Step Guide with Examples

1. += Add and Assign

x = 10
x += 5  # same as x = x + 5
print(x)  # Output: 15

In Machine Learning: Used when summing up loss during training.

total_loss = 0
for loss in batch_losses:
    total_loss += loss

2. -= Subtract and Assign

accuracy = 100
accuracy -= 2
print(accuracy)  # Output: 98

ML Use: Can be used in learning rate schedules:

learning_rate = 0.1
learning_rate -= 0.01

3. *= Multiply and Assign

scale = 3
scale *= 2
print(scale)  # Output: 6

ML Use: Common in backpropagation when scaling gradients:

gradient *= momentum_factor

4. /= Divide and Assign

total = 100
total /= 4
print(total)  # Output: 25.0

ML Use: Used to calculate averages (e.g. average loss):

average_loss = total_loss
average_loss /= len(batch)

5. //= Floor Division and Assign

samples = 101
samples //= 10
print(samples)  # Output: 10

ML Use: Used to compute how many batches we can get from a dataset.

6. %= Modulo and Assign

epoch = 5
epoch %= 2
print(epoch)  # Output: 1

ML Use: Useful when running actions every N steps:

if step % 10 == 0:
    print("Logging progress")

7. **= Power and Assign

base = 2
base **= 3
print(base)  # Output: 8

ML Use: Can be used to implement learning rate decay:

lr_decay = 0.95
learning_rate *= lr_decay ** epoch

8. Bitwise Compound Operators (advanced but useful)

&= Bitwise AND

a = 6  # binary 110
a &= 3  # binary 011
print(a)  # Output: 2 (binary 010)

|= Bitwise OR

a = 4
a |= 1
print(a)  # Output: 5

^= Bitwise XOR

a = 5
a ^= 3
print(a)  # Output: 6

<<= Left Shift

a = 2
a <<= 1
print(a)  # Output: 4

>>= Right Shift

a = 4
a >>= 1
print(a)  # Output: 2

Summary Table: Quick Reference

Compound Operator	Meaning	Example (x = 4, y = 2)	Result
x += y	Addition	x += 2	6
x -= y	Subtraction	x -= 2	2
x *= y	Multiplication	x *= 2	8
x /= y	Division	x /= 2	2.0
x //= y	Floor Division	x //= 2	2
x %= y	Modulo	x %= 2	0
x **= y	Power	x **= 2	16

Keywords

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