주변분포와 조건부분포

import numpy as np
import scipy
from scipy import linalg as la
import matplotlib.pyplot as plt

import scipy.stats as ss
import sympy

from pgmpy.factors.discrete import JointProbabilityDistribution as JPD
import pgmpy

# 결합 확률 정의
prob=list()
for i in np.arange(1,4):
    for j in np.arange(1,3):
        prob.append((i+j)/21)
        
fxy=JPD(['X1','X2'],[3,2],prob)
print(fxy)

np.sum(fxy.values)
# 1.0

# 주변 확률 구하기
fx=fxy.marginal_distribution(['X1'],inplace=False)
print(fx)

prob=fxy.conditional_distribution([('X1',0)],inplace=False)
print(prob)

 

 조건부확률밀도함수도 다음과 같이 확률밀도함수의 조건을 충족한다.