Array dimensionality

Introduzione a NumPy

Izzy Weber

Core Curriculum Manager, DataCamp

3D arrays

array_1_2D = np.array([[1, 2], [5, 7]])
array_2_2D = np.array([[8, 9], [5, 7]])
array_3_2D = np.array([[1, 2], [5, 7]])
array_3D = np.array([array_1_2D, array_2_2D, array_3_2D])

graphic of a 3D array

4D arrays

array_4D = np.array([array_A_3D, array_B_3D, array_C_3D, array_D_3D, array_E_3D,
                     array_F_3D, array_G_3D, array_H_3D, array_I_3D])

graphic of a 4D array

Vector arrays

Graphic showing that 1D arrays cannot be vertical or horizontal in NumPy

Graphic showing that 2D arrays can be vertical or horizontal in NumPy

Matrix and tensor arrays

A matrix has two dimensions

graphic of a matrix

A tensor has three or more dimensions

graphic of a tensor

Shapeshifting

Array attribute:

.shape

Array methods:

.flatten()
.reshape()

Finding an array's shape

array = np.zeros((3, 5))
print(array)

array([[0., 0., 0., 0., 0.],
       [0., 0., 0., 0., 0.],
       [0., 0., 0., 0., 0.]])

array.shape

(3, 5)

Rows and columns

In 2D arrays...

Rows are the first dimension
Columns are the second dimension

2D array with row and column labels

Flattening an array

array = np.array([[1, 2], [5, 7], [6, 6]])
array.flatten()

array([1, 2, 5, 7, 6, 6])

Reshaping an array

array = np.array([[1, 2], [5, 7], [6, 6]])
array.reshape((2, 3))

array([[1, 2, 5],
       [7, 6, 6]])

array.reshape((3, 3))

ValueError: cannot reshape array of size 6 into shape (3,3)

Let's practice!

Introduzione a NumPy