In a module created by the user, how can the columns of a matrix be accessed using their names?

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If the matrix was created using a pandas DataFrame, the columns can be accessed using their names with the following syntax:

df['column_name']

If the matrix was created using a numpy array, the columns can be accessed by indexing the array with the column number, like this:

arr[:, column_number]

Alternatively, the numpy array can be converted into a pandas DataFrame and the columns can be accessed as described above.