CODEWITHSUNDEEP
pythonscikit-learngini
Ming
Ming

Reputation: 71

How can I get Gini Coefficient in sklearn

I would like in sklearn package, Find the gini coefficients for each feature on a class of paths such as in iris data. like Iris-virginica Petal length gini：0.4 ，Petal width gini：0.4.

Upvotes: 6

Views: 18537

Answers (2)

Scriddie
Scriddie

Reputation: 3781

Not sklearn, but this is based on the Lorenz curve definition and should do the trick:

import numpy as np

def gini(x):
    return np.sum(np.abs(np.subtract.outer(x, x)))/(2*len(x)**2*x.mean())

Upvotes: 0

Martin Thoma
Martin Thoma

Reputation: 136437

You can calculate the gini coefficient with Python+numpy like this:

from typing import List
from itertools import combinations

import numpy as np

def gini(x: List[float]) -> float:
    x = np.array(x, dtype=np.float32)
    n = len(x)
    diffs = sum(abs(i - j) for i, j in combinations(x, r=2))
    return diffs / (2 * n**2 * x.mean())

Upvotes: 6

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