# How to Convert a 2D List to a 1D List in Python?

To convert a 2D list to a 1D list in Python, you can use list comprehension along with the `extend()` method. Here’s an example:

``````# Define a 2D list
list_2d = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

# Convert 2D list to 1D list using list comprehension and extend method
list_1d = []
[list_1d.extend(row) for row in list_2d]

# Print the 1D list
print(list_1d)``````

In this example, we have a 2D list `list_2d` containing multiple rows, each representing a list of elements.

To convert the 2D list to a 1D list, we first initialize an empty list `list_1d`. Then, we use list comprehension to iterate over each row in the 2D list and extend `list_1d` by appending the elements of each row.

The `extend()` method is used to append multiple elements to an existing list. It takes an iterable as an argument and adds each element to the list.

The output will be:

``[1, 2, 3, 4, 5, 6, 7, 8, 9]``

In this case, the 2D list `list_2d` is converted to a 1D list `list_1d` that contains all the elements from the original 2D list in a flattened manner.

Note that the order of the elements in the resulting 1D list is determined by the order of the rows in the 2D list. Adjust the logic according to your specific requirements.