Products
To find the product of the elements in an array, use the prod() function.
Example
Find the product of the elements of this array:
python
import numpy as np
arr = np.array([1, 2, 3, 4])
x = np.prod(arr)
print(x)
Returns:
24because 1234 = 24
Example
Find the product of the elements of two arrays:
python
import numpy as np
arr1 = np.array([1, 2, 3, 4])
arr2 = np.array([5,
6, 7, 8])
x = np.prod([arr1, arr2])
print(x)
Returns:
40320because 12345678 = 40320
Product Over an Axis
If you specify axis=1, NumPy will return the product of each array.
Example
Perform summation in the following array over 1st axis:
python
import numpy as np
arr1 = np.array([1, 2, 3, 4])
arr2 = np.array([5,
6, 7, 8])
newarr = np.prod([arr1, arr2], axis=1)
print(newarr)
Returns:
[24 1680]
Cummulative Product
Cummulative product means taking the product partially.
E.g. The partial product of [1, 2, 3, 4] is [1, 12, 123, 1234] = [1, 2, 6, 24]
Perfom partial sum with the cumprod() function.
Example
Take cummulative product of all elements for following array:
python
import numpy as np
arr = np.array([5,
6, 7, 8])
newarr = np.cumprod(arr)
print(newarr)
Returns:
[5 30 210 1680]