# Python Copy Module (Shallow vs Deep Copy)

Assignment statements in Python do not copy objects, they create bindings between a target and an object. For collections that are mutable or contain mutable items, a copy is sometimes needed so one can change one copy without changing the other.

## Importing the Module

```python
import copy
```

## Shallow Copy

A shallow copy constructs a new compound object and then (to the extent possible) inserts references into it to the objects found in the original.

```python
import copy

old_list = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
new_list = copy.copy(old_list)

# Modify the new list
new_list[0][0] = 'a'

print("Old list:", old_list)
print("New list:", new_list)
# Output:
# Old list: [['a', 2, 3], [4, 5, 6], [7, 8, 9]]
# New list: [['a', 2, 3], [4, 5, 6], [7, 8, 9]]
```

## Deep Copy

A deep copy constructs a new compound object and then, recursively, inserts copies into it of the objects found in the original.

```python
import copy

old_list = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
new_list = copy.deepcopy(old_list)

# Modify the new list
new_list[0][0] = 'a'

print("Old list:", old_list)
print("New list:", new_list)
# Output:
# Old list: [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
# New list: [['a', 2, 3], [4, 5, 6], [7, 8, 9]]
```

[[programming/python/python]]