pomegranate库调用报错：DiscreteDistribution未定义问题求助

我在运行CS50人工智能课程中涉及pomegranate概率模型库的示例代码时遇到了问题。

示例代码：

from pomegranate import *

class Node():
    def __init__(self, distribution, name):
        self.distribution = distribution
        self.name = name

# Rain node has no parents
rain = Node(DiscreteDistribution({
    "none": 0.7,
    "light": 0.2,
    "heavy": 0.1
}), name="rain")

# Track maintenance node is conditional on rain
maintenance = Node(ConditionalProbabilityTable([
    ["none", "yes", 0.4],
    ["none", "no", 0.6],
    ["light", "yes", 0.2],
    ["light", "no", 0.8],
    ["heavy", "yes", 0.1],
    ["heavy", "no", 0.9]
], [rain.distribution]), name="maintenance")

# Train node is conditional on rain and maintenance
train = Node(ConditionalProbabilityTable([
    ["none", "yes", "on time", 0.8],
    ["none", "yes", "delayed", 0.2],
    ["none", "no", "on time", 0.9],
    ["none", "no", "delayed", 0.1],
    ["light", "yes", "on time", 0.6],
    ["light", "yes", "delayed", 0.4],
    ["light", "no", "on time", 0.7],
    ["light", "no", "delayed", 0.3],
    ["heavy", "yes", "on time", 0.4],
    ["heavy", "yes", "delayed", 0.6],
    ["heavy", "no", "on time", 0.5],
    ["heavy", "no", "delayed", 0.5],
], [rain.distribution, maintenance.distribution]), name="train")

# Appointment node is conditional on train
appointment = Node(ConditionalProbabilityTable([
    ["on time", "attend", 0.9],
    ["on time", "miss", 0.1],
    ["delayed", "attend", 0.6],
    ["delayed", "miss", 0.4]
], [train.distribution]), name="appointment")

# Create a Bayesian Network and add states
model = BayesianNetwork()
model.add_states(rain, maintenance, train, appointment)

# Add edges connecting nodes
model.add_edge(rain, maintenance)
model.add_edge(rain, train)
model.add_edge(maintenance, train)
model.add_edge(train, appointment)

# Finalize model
model.bake()

已尝试的操作：

• 执行pip install pomegranate安装库
• 将pip更新至最新版本

报错信息：

rain = Node(DiscreteDistribution({
                ^^^^^^^^^^^^^^^^^^^^
NameError: name 'DiscreteDistribution' is not defined

尽管DiscreteDistribution、ConditionalProbabilityTable及BayesianNetwork均为pomegranate官网列明的函数，仍出现未定义错误，希望得到解决。

这个错误源于pomegranate v0.14+版本的API重构：原顶层类被移至子模块，且网络节点要求使用内置State对象，而非自定义节点类。可通过以下方式解决：

方式一：适配新版本API的完整修改代码 #

替换自定义Node类为pomegranate内置的State类，并调整导入路径：

from pomegranate import State, DiscreteDistribution, ConditionalProbabilityTable, BayesianNetwork

# Rain node has no parents
rain = State(DiscreteDistribution({
    "none": 0.7,
    "light": 0.2,
    "heavy": 0.1
}), name="rain")

# Track maintenance node is conditional on rain
maintenance = State(ConditionalProbabilityTable([
    ["none", "yes", 0.4],
    ["none", "no", 0.6],
    ["light", "yes", 0.2],
    ["light", "no", 0.8],
    ["heavy", "yes", 0.1],
    ["heavy", "no", 0.9]
], [rain.distribution]), name="maintenance")

# Train node is conditional on rain and maintenance
train = State(ConditionalProbabilityTable([
    ["none", "yes", "on time", 0.8],
    ["none", "yes", "delayed", 0.2],
    ["none", "no", "on time", 0.9],
    ["none", "no", "delayed", 0.1],
    ["light", "yes", "on time", 0.6],
    ["light", "yes", "delayed", 0.4],
    ["light", "no", "on time", 0.7],
    ["light", "no", "delayed", 0.3],
    ["heavy", "yes", "on time", 0.4],
    ["heavy", "yes", "delayed", 0.6],
    ["heavy", "no", "on time", 0.5],
    ["heavy", "no", "delayed", 0.5],
], [rain.distribution, maintenance.distribution]), name="train")

# Appointment node is conditional on train
appointment = State(ConditionalProbabilityTable([
    ["on time", "attend", 0.9],
    ["on time", "miss", 0.1],
    ["delayed", "attend", 0.6],
    ["delayed", "miss", 0.4]
], [train.distribution]), name="appointment")

# Create a Bayesian Network and add states
model = BayesianNetwork()
model.add_states(rain, maintenance, train, appointment)

# Add edges connecting nodes
model.add_edge(rain, maintenance)
model.add_edge(rain, train)
model.add_edge(maintenance, train)
model.add_edge(train, appointment)

# Finalize model
model.bake()

方式二：显式导入所需类（兼容自定义Node类场景） #

若需保留自定义Node类，需修改导入语句指定子模块路径：

from pomegranate.distributions import DiscreteDistribution, ConditionalProbabilityTable
from pomegranate.bayesian_network import BayesianNetwork

注意：此方式仅解决导入问题，新版本BayesianNetwork.add_states仍要求传入State对象，自定义Node类无法直接使用，建议优先采用方式一。

内容的提问来源于stack exchange，提问作者Ivan