6.15 Subgroups Right

Subgoups Right

R figure

Python figure

Code

import numpy as np
import matplotlib.pyplot as plt
from math import log2, sqrt

c = 1
pos = c * 50
neg = 50

def entropy(P, N):
    if P == 0 or N == 0:
        return 0
    p = P / (P + N)
    n = N / (P + N)
    return -p * log2(p) - n * log2(n)

def gini(P, N):
    p = P / (P + N)
    n = N / (P + N)
    return 4 * p * n

def dkm(P, N):
    p = P / (P + N)
    n = N / (P + N)
    return 2 * sqrt(p * n)

def metric(tp, fp, m):
    Pos = pos
    Neg = neg
    N = Pos + Neg
    TP = tp
    FP = fp
    FN = Pos - TP
    TN = Neg - FP

    if tp + fp == 0:
        return 0

    if m == 'accuracy':
        return (TP + TN) / N
    elif m == 'wracc':
        return TP / N - (TP + FP) * (TP + FN) / (N ** 2)
    elif m == 'precision':
        return TP / (TP + FP)
    elif m == 'f-measure':
        return 2 * TP / (2 * TP + FP + FN)
    elif m == 'gini':
        return gini(Pos, Neg) - ((TP + FP) / N) * gini(TP, FP) - ((FN + TN) / N) * gini(FN, TN)
    elif m == 'entropy':
        return ((TP + FP) / N) * entropy(TP, FP)
    elif m == 'dkm':
        return dkm(Pos, Neg) - ((TP + FP) / N) * dkm(TP, FP) - ((FN + TN) / N) * dkm(FN, TN)
    else:
        return 0

def rocgrid():
    fig, ax = plt.subplots(figsize=(6, 6))
    ax.set_xlim(0, neg)
    ax.set_ylim(0, pos)
    ax.set_xlabel('Negatives')
    ax.set_ylabel('Positives')
    ax.set_xticks(np.arange(0, neg+1, 10))
    ax.set_yticks(np.arange(0, pos+1, 10))
    ax.grid(True, color='gray', linestyle='--', linewidth=0.5)
    return ax

def contour1(ax, m, color, linestyle, tp, fp):
    x = np.arange(0, neg+1)
    y = np.arange(0, pos+1)
    Z = np.zeros((len(y), len(x)))

    for i, xi in enumerate(x):
        for j, yj in enumerate(y):
            Z[j, i] = metric(yj, xi, m)

    v = metric(tp, fp, m)
    CS = ax.contour(x, y, Z, levels=[v], colors=color, linestyles=linestyle)
    ax.plot(fp, tp, 'o', color=color)

ax = rocgrid()
method = 'wracc'
d = 1

contour1(ax, method, 'red', 'solid',   0, 40)
contour1(ax, method, 'black', 'dotted', 10, 30)
contour1(ax, method, 'black', 'dotted', 20, 20)
contour1(ax, method, 'black', 'dotted', 20, 0)
contour1(ax, method, 'orange', 'solid', 50, 10)
contour1(ax, method, 'black', 'dotted', 50, 30)
contour1(ax, method, 'black', 'dotted', 0, 20)
contour1(ax, method, 'black', 'dotted', 30, 40)
contour1(ax, method, 'black', 'dotted', 20, 10)

plt.title("Curvas de nível para a métrica 'wracc'")
plt.show()