﻿ Python: Create a deep copy of a given list - w3resource # Python: Create a deep copy of a given list

## Python module: Exercise-2 with Solution

Write a Python program to create a deep copy of a given list. Use copy.copy

Sample Solution:

Python Code:

``````import copy
nums_x = [1, [2, 3, 4]]
print("Original list: ", nums_x)
nums_y = copy.deepcopy(nums_x)
print("\nDeep copy of the said list:")
print(nums_y)
print("\nChange the value of an element of the original list:")
nums_x = 10
print(nums_x)
print("\nCopy of the second list (Deep copy):")
print(nums_y)
nums = [[1, 2, 3], [4, 5, 6]]
deep_copy = copy.deepcopy(nums)
print("\nOriginal list:")
print(nums)
print("\nDeep copy of the said list:")
print(deep_copy)
print("\nChange the value of some elements of the original list:")
nums = 55
nums = 77
print("\nOriginal list:")
print(nums)
print("\nSecond list (Deep copy):")
print(deep_copy)
```
```

Sample Output:

```Original list:  [1, [2, 3, 4]]

Deep copy of the said list:
[1, [2, 3, 4]]

Change the value of an element of the original list:
[1, [2, 10, 4]]

Copy of the second list (Deep copy):
[1, [2, 3, 4]]

Original list:
[[1, 2, 3], [4, 5, 6]]

Deep copy of the said list:
[[1, 2, 3], [4, 5, 6]]

Change the value of some elements of the original list:

Original list:
[[1, 2, 55], [4, 77, 6]]

Second list (Deep copy):
[[1, 2, 3], [4, 5, 6]]
```

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The following tool visualize what the computer is doing step-by-step as it executes the said program:

Python Code Editor:

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## Python: Tips of the Day

For-else construct useful when searched for something and find it:

```# For example assume that I need to search through a list and process each item until a flag item is found and
# then stop processing. If the flag item is missing then an exception needs to be raised.

for i in mylist:
if i == theflag:
break
process(i)
else:
raise ValueError("List argument missing terminal flag.")
```