Numpy is the best libraries for doing complex manipulation on the arrays. It’s very easy to make a computation on arrays using the Numpy libraries. Array manipulation is somewhat easy but I see many new beginners or intermediate developers find difficulties in matrices manipulation. In this section of how to, you will learn how to create a matrix in python using Numpy.
What is a matrix?
Matrix is a two-dimensional array. In numpy, you can create two-dimensional arrays using the array() method with the two or more arrays separated by the comma. You can read more about matrix in details on Matrix Mathematics.
array1 = np.array([1,2,3]) array2 = np.array([4,5,6]) matrix1 = np.array([array1,array2]) matrix1
How to create a matrix in a Numpy?
There is another way to create a matrix in python. It is using the numpy matrix() methods. It is the lists of the list. For example, I will create three lists and will pass it the matrix() method.
list1 = [2,5,1] list2 = [1,3,5] list3 = [7,5,8] matrix2 = np.matrix([list1,list2,list3]) matrix2
You can also find the dimensional of the matrix using the matrix_variable.shape. The matrix2 is of (3,3) dimension.
How to find the transpose of a matrix?
Transpose is a new matrix result from when all the elements of rows are now in column and vice -versa. You can find the transpose of a matrix using the matrix_variable .T. Like, in this case, I want to transpose the matrix2.
How to find the Inverse of a Matrix?
You can find the inverse of the matrix using the matrix_variable.I.
To verify that this Inverse, you can multiply the original matrix with the Inverted Matrix and you will get the Identity matrix.
matrix2 * matrix2.I
How to solve the Simultaneous Linear Equations?
In a matrix, you can solve the linear equations using the matrix. For example, you have the following three equations.
1) x + y − z = 4
2) x − 2y + 3z = −6
3) 2x + 3y + z = 7
First, you will create a matrix containing constants of each of the variable x,y,x or the left side. Then the matrix for the right side.
left_hand_side = np.matrix([[1,1,-1], # x + y − z = 4 [1,-2,3], # x − 2y + 3z = −6 [2,3,1]]) # 2x + 3y + z = 7 left_hand_side
right_hand_side = np.matrix([, [-6], ]) right_hand_side
To find out the solution you have to first find the inverse of the left-hand side matrix and multiply with the right side.
left_hand_side_inverse = left_hand_side.I left_hand_side_inverse
solution = left_hand_side_inverse*right_hand_side solution
You can verify the solution is correct or not by the following
left_hand_side*solution - right_hand_side
Matrix is widely used by the data scientist for data manipulation. After reading this tutorial, I hope you are able to manipulate the matrix. If you have any question regarding this then contact us we are always ready to help you.