# Python | Ways to Convert a 3D list into a 2D list

• Last Updated : 02 Aug, 2019

List is a common type of data structure in Python. While we have used the list and 2d list, the use of 3d list is increasing day by day, mostly in case of web development.
Given a 3D list, the task is to convert it into a 2D list. These type of problems are encountered while working on projects or while contributing to open source.
Below are some ways to achieve the above task.

```Input:
[[[3], [4]], [[5], [6]], [[7], [8]]]
Output:
[[3], [4], [5], [6], [7], [8]]
```

Method #1: Using simple iteration to convert a 3D list into a 2D list.

 `# Python code to convert a 3D list into a 2D list`` ` `# Input list initialization``Input` `=` `[[[``3``], [``4``]], [[``5``], [``6``]], [[``7``], [``8``]]]`` ` `# Output list initialization``Output ``=` `[]`` ` `# Using iteration``for` `temp ``in` `Input``:``    ``for` `elem ``in` `temp:``        ``Output.append(elem)`` ` `# printing output``print``(``"Initial 3d list is"``)``print``(``Input``)``print``(``"Converted 2d list is"``)``print``(Output)`

Output:

```Initial 3d list is
[[[3], [4]], [[5], [6]], [[7], [8]]]
Converted 2d list is
[[3], [4], [5], [6], [7], [8]]
```

Method #2: Using List Comprehension to convert a 3D list into a 2D list

 `# Python code to convert a 3D list into a 2D list`` ` `# Input list initialization``Input` `=` `[[[``1``, ``1``], [``2``, ``7``]], [[``3``], [``4``]], [[``6``, ``5``], [``6``]]]`` ` `# Using list comprehension``Output ``=` `[elem ``for` `twod ``in` `Input` `for` `elem ``in` `twod]`` ` `# printing output``print``(``"Initial 3d list is"``)``print``(``Input``)``print``(``"Converted 2d list is"``)``print``(Output)`

Output:

```Initial 3d list is
[[[1, 1], [2, 7]], [[3], [4]], [[6, 5], [6]]]
Converted 2d list is
[[1, 1], [2, 7], [3], [4], [6, 5], [6]]
```

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