Normalize Array

Problem Statement

Normalize array data using broadcasting.

Background

Normalization scales data to a standard range. Common methods:

• Min-max: (x - min) / (max - min) → scales to [0, 1]
• Z-score: (x - mean) / std → centers around 0

These operations use broadcasting naturally.

Your Task

Write a function normalize(arr) that normalizes a 2D array column-wise.

Output Format

Return a dictionary with:

• "minmax": Min-max normalized (rounded to 3 decimals)
• "zscore": Z-score normalized (rounded to 3 decimals)
• "col_means": Mean of each column before normalization (rounded to 2 decimals)
• "col_stds": Std of each column before normalization (rounded to 2 decimals)