AssertionError: model.start 应该有两条边，Rainy 有两条，Sunny 有两条答案

【问题标题】：AssertionError: There should be two edges from model.start, two from Rainy, and two from SunnyAssertionError: model.start 应该有两条边，Rainy 有两条，Sunny 有两条
【发布时间】：2019-12-14 01:39:06
【问题描述】：

当我在 HMM 中制作模型时遇到问题 AssertionError 但无法弄清楚问题是什么？

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
from helpers import show_model
from pomegranate import State, HiddenMarkovModel, DiscreteDistribution



model = HiddenMarkovModel(name='Example Model')

#Emission probabiliy of distributions, p(umbrella|weather)
sunny_emission = DiscreteDistribution({'yes':0.1, 'no':0.8})
sunny_state = State(sunny_emission, name='Sunny')

rainy_emission = DiscreteDistribution({'yes':0.8, 'no':0.2})
rainy_state = State(rainy_emission, name='rainy')


model.add_states(sunny_state, rainy_state)

assert rainy_emission.probability('yes') == 0.8, "The director brings his umbrella with probability 0.8 on rainy days"
print("looks good so far")

model.add_transition(model.start, sunny_state, 0.5)
model.add_transition(model.start, rainy_state, 0.5)


model.add_transition(sunny_state, sunny_state, 0.8) # 80%sunny days
model.add_transition(rainy_state, rainy_state, 0.2) # 20% rainy days


model.add_transition(rainy_state, rainy_state, 0.6)
model.add_transition(rainy_state, sunny_state, 0.4)

model.bake()


assert model.edge_count() == 6, "There should be two edges from model.start, two from Rainy, and two from Sunny"
assert model.node_count() == 4, "The states should include model.start, model.end, Rainy, and Sunny"

AssertionError: model.start 应该有两条边，Rainy 有两条，Sunny 有两条

【问题讨论】：

标签： python-3.x machine-learning nlp hidden-markov-models pomegranate

【解决方案1】：

您收到该错误的原因是，您的代码中只有 5 条来自隐藏状态 ('SUNNY') 的边，但 assert 语句正在检查 6 条边。

**model.add_transition(rainy_state, rainy_state, 0.2) # 20% rainy days**

这是错误所在的行，这里的过渡是从“下雨到下雨”而不是“晴天到下雨”。

【讨论】：