Standardization of Feature Values

Problem

Standardize values to zero mean and unit variance using the population variance (divide by n): z_i = (x_i - mean) / std.

If the variance is 0, return a list of zeros. Empty input returns [].

Hint

The population standard deviation divides the squared deviations by n, not n-1.

case 1

in: [[1,2,3]]

expected: [-1.224744871391589,0,1.224744871391589]

case 2

in: [[0,0,10,10]]

expected: [-1,-1,1,1]

case 3

in: [[5,5,5]]

expected: [0,0,0]

case 4

in: [[]]

expected: []

Starter codePython

def standardize(values):
    # Your code here
    pass

4 test cases · run your code against them in the editor