NumPy Broadcasting | Dataford Interview Questions

What is broadcasting in a NumPy array and what is it used for?

Asked in the 1st Round Technical Interview stage. Demonstrate the concept by implementing broadcasting for element-wise addition without importing NumPy.

Task

Implement broadcast_add(a, b), where each input is a scalar or a rectangular nested Python list of numbers. Align dimensions from the right. Two dimensions are compatible when they are equal or one is 1. Return a new nested list with the broadcasted shape containing element-wise sums.

Constraints

Each input is a number or a rectangular nested Python list of numbers.
Every list dimension contains at least one element.
The input shapes are broadcast-compatible.
The number of dimensions is at most 6.
The total number of output elements is at most 100000.

Function Signature

def broadcast_add(a, b):

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Problem