def compute(obs, states, start_p, trans_p, emit_p): # max_p(3*2)每一列存储第一列不同隐状态的最大概率 max_p = np.zeros((len(obs), len(states))) path = np.zeros((len(states), len(obs))) # 初始化 for i in range(len(states)): max_p[0][i] = start_p[i] * emit_p[i][obs[0]] path[i][0] = i for t in range(1, len(obs)): newpath = np.zeros((len(states), len(obs))) for y in range(len(states)): prob = -1 for y0 in range(len(states)): nprob = max_p[t-1][y0] * trans_p[y0][y] * emit_p[y][obs[t]] if nprob > prob: prob = nprob state = y0 # 记录路径 max_p[t][y] = prob for m in range(t): newpath[y][m] = path[state][m] newpath[y][t] = y path = newpath请给这段代码的每行代码加上详细注释以及每一行所涉及到的函数
时间: 2024-02-14 19:13:59 浏览: 68
```
import numpy as np
def compute(obs, states, start_p, trans_p, emit_p):
# max_p(3*2)每一列存储第一列不同隐状态的最大概率
max_p = np.zeros((len(obs), len(states)))
path = np.zeros((len(states), len(obs)))
# 初始化
for i in range(len(states)):
max_p[0][i] = start_p[i] * emit_p[i][obs[0]]
path[i][0] = i
# 遍历观测序列
for t in range(1, len(obs)):
# 初始化新路径矩阵
newpath = np.zeros((len(states), len(obs)))
# 遍历所有可能的状态
for y in range(len(states)):
# 初始化最大概率和最大概率对应的路径
prob = -1
state = None
# 遍历上一时刻所有可能的状态
for y0 in range(len(states)):
# 计算概率
nprob = max_p[t-1][y0] * trans_p[y0][y] * emit_p[y][obs[t]]
# 更新最大概率和对应的路径
if nprob > prob:
prob = nprob
state = y0
# 记录路径
max_p[t][y] = prob
for m in range(t):
newpath[y][m] = path[state][m]
newpath[y][t] = y
# 更新路径矩阵
path = newpath
return path
```
以上是对这段代码的详细注释,以及每一行所涉及到的函数:
1. `import numpy as np`:导入NumPy库,用于处理数组和矩阵等数值计算。
2. `def compute(obs, states, start_p, trans_p, emit_p):`:定义一个函数`compute`,接收五个参数,分别是观测序列`obs`、隐状态集合`states`、初始概率矩阵`start_p`、转移概率矩阵`trans_p`和发射概率矩阵`emit_p`。
3. `max_p = np.zeros((len(obs), len(states)))`:初始化一个形状为`(len(obs), len(states))`的全零矩阵`max_p`,用于存储计算过程中的最大概率值。
4. `path = np.zeros((len(states), len(obs)))`:初始化一个形状为`(len(states), len(obs))`的全零矩阵`path`,用于存储计算过程中的路径。
5. `for i in range(len(states)): max_p[0][i] = start_p[i] * emit_p[i][obs[0]] path[i][0] = i`:遍历隐状态集合`states`,初始化`max_p`和`path`的第一列。
6. `for t in range(1, len(obs)): newpath = np.zeros((len(states), len(obs)))`:遍历观测序列`obs`,初始化新路径矩阵`newpath`。
7. `for y in range(len(states)): prob = -1 for y0 in range(len(states)): nprob = max_p[t-1][y0] * trans_p[y0][y] * emit_p[y][obs[t]] if nprob > prob: prob = nprob state = y0`:遍历隐状态集合`states`,计算到达当前状态`y`的最大概率值和对应的路径。
8. `max_p[t][y] = prob for m in range(t): newpath[y][m] = path[state][m] newpath[y][t] = y`:更新`max_p`和`newpath`矩阵。
9. `path = newpath`:更新路径矩阵`path`。
10. `return path`:返回路径矩阵`path`。
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