Get the Outer product of two multidimensional arrays in Python

To get the Outer product of two multi-dimensional arrays, use the numpy.outer() method in Python. The 1st parameter a is the first input vector. Input is flattened if not already 1-dimensional. The 2nd parameter b is the second input vector. Input is flattened if not already 1-dimensional. The 3rd parameter out is a location where the result is stored.

Given two vectors, a = [a0, a1, ..., aM] and b = [b0, b1, ..., bN], the outer product [1] is −

[[a0*b0 a0*b1 ... a0*bN ]
[a1*b0 .
[ ... .
[aM*b0    aM*bN ]]

Steps

At first, import the required libraries −

import numpy as np

Creating two numpy Two-Dimensional array using the array() method −

arr1 = np.array([[5, 10], [15, 20]])
arr2 = np.array([[6, 12], [18, 24]])

Display the arrays −

print("Array1...\n",arr1)
print("\nArray2...\n",arr2)

Check the Dimensions of both the arrays −

print("\nDimensions of Array1...\n",arr1.ndim)
print("\nDimensions of Array2...\n",arr2.ndim)

Check the Shape of both the arrays −

print("\nShape of Array1...\n",arr1.shape)
print("\nShape of Array2...\n",arr2.shape)

To get the Outer product of two multi-dimensional arrays, use the numpy.outer() method −

print("\nResult (Outer Product)...\n",np.outer(arr1, arr2))

Example

import numpy as np

# Creating two numpy Two-Dimensional array using the array() method
arr1 = np.array([[5, 10], [15, 20]])
arr2 = np.array([[6, 12], [18, 24]])

# Display the arrays
print("Array1...\n",arr1)
print("\nArray2...\n",arr2)

# Check the Dimensions of both the arrays
print("\nDimensions of Array1...\n",arr1.ndim)
print("\nDimensions of Array2...\n",arr2.ndim)

# Check the Shape of both the arrays
print("\nShape of Array1...\n",arr1.shape)
print("\nShape of Array2...\n",arr2.shape)

# To get the Outer product of two multi-dimensional arrays, use the numpy.outer() method in Python
print("\nResult (Outer Product)...\n",np.outer(arr1, arr2))

Output

Array1...
[[ 5 10]
[15 20]]

Array2...
[[ 6 12]
[18 24]]

Dimensions of Array1...
2

Dimensions of Array2...
2

Shape of Array1...
(2, 2)

Shape of Array2...
(2, 2)

Result (Outer Product)...
[[ 30 60 90 120]
[ 60 120 180 240]
[ 90 180 270 360]
[120 240 360 480]]