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# Python | Type casting whole List and Matrix

• Last Updated : 30 Dec, 2020

Sometimes, while working with Python List or Matrix, we usually have a problem in which we require to get a generalized function which could perform the type casting of whole container at once. There is always a need of a mechanism code which can transform entirely the allowed change of data type for all elements in container. Let’s discuss a way in which this task can be performed.

Method : Using `map()` + list comprehension
This task can be performed using a map(). The transformation of a normal list can be performed using a single map function by just passing the desired data type. But when it comes to transformation of whole matrix, we need the help of list comprehension for the same.

 `# Python3 code to demonstrate working of``# Type casting whole List and Matrix``# using map() + list comprehension`` ` `# helper function to type cast list ``def` `cast_list(test_list, data_type):``    ``return` `list``(``map``(data_type, test_list))``     ` `# helper function to type cast Matrix ``def` `cast_matrix(test_matrix, data_type):``    ``return` `list``(``map``(``lambda` `sub: ``list``(``map``(data_type, sub)), test_matrix))``     ` `# initialize list ``test_list ``=` `[``1``, ``4``, ``9``, ``10``, ``19``]`` ` `# initialize Matrix``test_matrix ``=` `[[``5``, ``6``, ``8``], [``8``, ``5``, ``3``], [``9``, ``10``, ``3``]]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# printing original matrix``print``(``"The original Matrix is : "` `+` `str``(test_matrix))`` ` `# Type casting whole List and Matrix``# using map() + list comprehension``res_list ``=` `cast_list(test_list, ``str``)``res_matrix ``=` `cast_matrix(test_matrix, ``str``)`` ` `# printing result``print``(``"The List after type casting is : "` `+` `str``(res_list))``print``(``"The Matrix after type casting is : "` `+` `str``(res_matrix))`
Output :
```The original list is : [1, 4, 9, 10, 19]
The original Matrix is : [[5, 6, 8], [8, 5, 3], [9, 10, 3]]
The List after type casting is : ['1', '4', '9', '10', '19']
The Matrix after type casting is : [['5', '6', '8'], ['8', '5', '3'], ['9', '10', '3']]
```

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