Python:NumPy .prod()

The .prod() function in NumPy returns the product of array elements over a specified axis. It’s useful in mathematical and statistical operations, especially with multi-dimensional arrays where the product needs to be computed across rows, columns, or the entire array. This function is also available as the standalone function numpy.prod().

Syntax

ndarray.prod(axis=None, dtype=None, out=None, keepdims=False, initial=1, where=True)

Parameters:

• axis (int or tuple of ints, optional): The axis or axes along which the product is computed.
  • If None (default), the product of all elements in the array is returned.
  • If an integer or tuple of integers, the product is computed along the specified axis or axes.
• dtype (Optional): The data type of the returned array and of the accumulator used in the computation. If not specified, it’s inferred from the input to avoid overflow when possible.
• out (ndarray, optional): An alternate output array in which to place the result. It must have the same shape as the expected output.
• keepdims (bool, optional): If True, the reduced axes are kept in the result as dimensions with size one. Default is False.
• initial (scalar, optional): The starting value for the product. The default is 1.
• where (array_like of bool, optional): A boolean array indicating elements to include in the product. Elements where where is False are ignored.

Return value:

Returns the product of array elements over the specified axis (or the entire array if axis=None). The returned type matches the input or the specified dtype.

Example

The following example shows the use of the .prod() to calculate the product of all elements in a 1D array and the product along the columns in a 2D array:

import numpy as np

# 1D array example
arr_1d = np.array([2, 3, 4])
product_all = arr_1d.prod()

# 2D array example
# [[1, 2],
#  [5, 6]]
arr_2d = np.array([[1, 2], [5, 6]])

# Product along columns (axis=0): (1*5, 2*6)
product_cols = arr_2d.prod(axis=0)

print(f"Product of all elements (1D): {product_all}")
print(f"Product along columns (axis=0) in 2D: {product_cols}")

Copy to clipboard
Copy to clipboard

The code above generates the following output:

Product of all elements (1D): 24
Product along columns (axis=0) in 2D: [ 5 12]

Copy to clipboard
Copy to clipboard

Codebyte Example

The following codebyte example demonstrates calculating the product of elements along the rows (axis=1) of a 2D array:

Visit us
Visit us
Hide code
Code
Output
Hide output
Loading...
Copy to your clipboard
Copy Codebyte
Run