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In data science and machine learning, features often exist on vastly different scales. For instance, one feature might range from 0 to 1, while another spans from 1,000 to 1,000,000. When these raw features are fed directly into algorithms, those with larger numerical ranges tend to dominate the learning process, leading to biased or suboptimal models.
Range-Bounded Feature Scaling (commonly known as min-max scaling) is a powerful normalization technique that transforms numerical values into a standardized interval, typically [0, 1]. This ensures that every feature contributes proportionally to the model, regardless of its original magnitude.
The Transformation Formula:
For a given value x in a dataset with minimum value x_min and maximum value x_max, the scaled value x' is computed as:
$$x' = \frac{x - x_{min}}{x_{max} - x_{min}}$$
This linear transformation guarantees that:
Handling Edge Cases:
When all values in the dataset are identical (i.e., x_min = x_max), the denominator becomes zero, making division undefined. In such cases, the function should return a list of zeros to indicate no meaningful variation exists in the data.
Your Task:
Implement a function that takes a list of numerical values and returns a new list where each value has been transformed to fall within the [0, 1] range using the formula above. Ensure proper handling of the edge case where all input values are the same.
values = [1, 2, 3, 4, 5][0.0, 0.25, 0.5, 0.75, 1.0]The minimum value is 1 and the maximum value is 5, giving a range of 4.
• Value 1: (1 - 1) / (5 - 1) = 0 / 4 = 0.0 • Value 2: (2 - 1) / (5 - 1) = 1 / 4 = 0.25 • Value 3: (3 - 1) / (5 - 1) = 2 / 4 = 0.5 • Value 4: (4 - 1) / (5 - 1) = 3 / 4 = 0.75 • Value 5: (5 - 1) / (5 - 1) = 4 / 4 = 1.0
The middle value (3) maps to 0.5, confirming it's exactly halfway between the extremes.
values = [10, 20, 30, 40, 50][0.0, 0.25, 0.5, 0.75, 1.0]Despite having different absolute values than the first example, the relative positions are identical.
• Value 10: (10 - 10) / (50 - 10) = 0 / 40 = 0.0 • Value 20: (20 - 10) / (50 - 10) = 10 / 40 = 0.25 • Value 30: (30 - 10) / (50 - 10) = 20 / 40 = 0.5 • Value 40: (40 - 10) / (50 - 10) = 30 / 40 = 0.75 • Value 50: (50 - 10) / (50 - 10) = 40 / 40 = 1.0
This demonstrates that scaling is invariant to the original magnitude—only relative positions matter.
values = [5, 5, 5, 5][0.0, 0.0, 0.0, 0.0]All values are identical (5), so minimum and maximum are both 5.
The range (max - min) equals zero, which would cause a division by zero error. In this special case, we return a list of zeros to indicate that there is no variation in the data—all points are effectively at the same position.
This edge case handling is crucial for robust preprocessing pipelines.
Constraints