関連ワード:  how to initialize a matrix in python    how to initialize a matrix in python using numpy    how to create a matrix in python    how to initialize a 2d array in python    how to declare a matrix in python    how to create a matrix in python using numpy    how to create a matrix in python using for loop    how to create a matrix in python without numpy    how to create a matrix in python using user input    how to create a matrix in python using list comprehension