Summary  
This chapter covers using the append() method to add elements to the end of a Python list, enabling dynamic list growth without recreating the list.  

General domain of usage  
Iterative data collection in loops.

The `append()` method in Python is used to add an element to the end of a list. It's a convenient way to expand a list dynamically without having to create a new one. 

Imagine you have a list of cities you want to visit. You've already listed a few, but as your plans evolve, you want to add more cities without replacing the existing ones.
```python
travel_wishlist = ["Paris", "Tokyo", "New York", "Rome"]
```
The list currently contains **four** cities. Now imagine you want to add another city, say "Sydney".
Here's how you can do it:

travel_wishlist = ['Paris', 'Tokyo', 'New York', 'Rome']

# Adding a new city to the travel wishlist
travel_wishlist.append("Sydney")

print(travel_wishlist) # Output: ['Paris', 'Tokyo', 'New York', 'Rome', 'Sydney']

As you can see, `"Sydney"` has been added to the end of the list without affecting the existing items.

- The list grows **by one element** every time you use `append()`;
-  You can append not only strings but also **variables**, **numbers**, or even other **lists**;
- The same logic applies to **integers**, **floats**, or any **object**.

Note

The `append()` method allows you to efficiently update your list without recreating it. Additionally, this method is especially practical in `for` loops, where you can dynamically build or grow a list by adding elements iteratively based on conditions or computations.

import unittest
from contextlib import redirect_stdout
import io
import importlib

def _dynamic_test(test_case, condition, success_message, failure_message):
    if condition:
        test_case._testMethodName = success_message
        test_case.assertTrue(True, success_message)
    else:
        test_case._testMethodName = failure_message
        test_case.fail(failure_message)

class TestUserCode(unittest.TestCase):

    def test_travel_wishlist_is_declared(self):
        import user_code
        _dynamic_test(
            self,
            hasattr(user_code, 'travel_wishlist'),
            "The `travel_wishlist` list is declared.",
            "Expected `travel_wishlist` to be declared."
        )

    def test_cities_added_to_list(self):
        import user_code
        expected_cities = ['Paris', 'Tokyo', 'Berlin', 'New York']
        _dynamic_test(
            self,
            user_code.travel_wishlist == expected_cities,
            f"The cities were added correctly to the list: {user_code.travel_wishlist}.",
            f"Expected travel_wishlist to be {expected_cities}, but got {user_code.travel_wishlist}."
        )

    def test_append_method_used(self):
        with open('user_code.py', 'r') as file:
            user_code_source = file.read()
        
        _dynamic_test(
            self,
            ".append(" in user_code_source,
            "The `append` method is used to add cities.",
            "Expected the `append` method to be used to add cities."
        )

if __name__ == '__main__':
    unittest.main()


test_main.py

Explore the fundamental data structures of the Python programming language, including lists, dictionaries, tuples, and sets, and learn how to apply them effectively to solve real-world programming challenges.

What is a list? A list is an ordered collection that can be modified. It also allows for duplicate elements.

Adding Elements to Lists in Python

解答