Python hmm

import re
import time
import math
# --- Parameter ---
FREQUENCY = 60 # (Hz)
DECIMAL = 3 # 2nd decimal place (About 70km)
ALPHA = 4.07 # Standard deviation of GPS measurement
'''
BETA value
'''
BETA = 1 # Exponential distribution parameter
# --- Structure ---
gps_data = [] # [(Latitude, Longitude) ...]
road_network = {} # {Edge ID: (From Node ID, To Node ID, Two Way, Speed
(m/s))}
road_list = [] # [(Edge ID, Segment ID, Latitude, Longitude, Status) ...] Status
0 - skip, 1 - do HMM
road_map = {} # {(Latitude(2nd decimal place), Longitude(2nd decimal
place)): [Edge ID, Segment ID, Latitude, Longitude ...])
ground_true = [] # (Edge, Traverse)
# --- Function ---
def deg2rad(d): # degree to radian
return d * math.pi / 180.0
EARTH_RADIUS_METER = 6378137.0
def spherical_distance(f, t): # caculate the spherical distance of two points
flat = deg2rad(f[0])
flon = deg2rad(f[1])
tlat = deg2rad(t[0])
tlon = deg2rad(t[1])
con = math.sin(flat) * math.sin(tlat)
con += math.cos(flat) * math.cos(tlat) * math.cos(flon - tlon)
return math.acos(con) * EARTH_RADIUS_METER # (m)

def route_distance(f, t):
'''
route algo
'''
return 0
def measure_probability(f, t):
return 1 / (math.sqrt(2 * math.pi) * ALPHA) * math.exp(-0.5 *
math.pow(spherical_distance(f, t) / ALPHA, 2))
def transition_probability(z1, z2, x1, x2):
return 1 / BETA * math.exp(-1 * (spherical_distance(z1, z2) - route_distance(x1,
x2)) / BETA)
'''
def viterbi(obs, states, start_p, trans_p, emit_p):
V = [{}]
path = {}
# Initialize base cases (t == 0)
for y in states:
V[0][y] = start_p[y] * emit_p[y][obs[0]]
path[y] = [y]
# Run Viterbi for t > 0
for t in range(1, len(obs)):
V.append({})
newpath = {}
for y in states:
(prob, state) = max((V[t-1][y0] * trans_p[y0][y] * emit_p[y][obs[t]], y0)
for y0 in states)
V[t][y] = prob
newpath[y] = path[state] + [y]
# Don't need to remember the old paths
path = newpath
n = 0 # if only one element is observed max is sought in the

initialization values
if len(obs)!=1:
n = t
print_dptable(V)
(prob, state) = max((V[n][y], y) for y in states)
return (prob, path[state])
'''
#====================================================================
=========================================#
# --- Parsing ---
print('Parsing...')
tStart = time.time() # (ms)
# [GPS data]
gps_data_file = open('gps_data.txt', 'r', encoding = 'UTF-8')
info = gps_data_file.readline() # [(Date (UTC), Time (UTC), Latitude, Longitude)
counter = 0
for line in gps_data_file:
counter += 1
if(counter == 60 / FREQUENCY):
temp = line.split()
gps_data.append((float(temp[2]), float(temp[3])))
counter = 0
print("GPS data (number): ", len(gps_data))
gps_data_file.close()
# [Road network data]
road_network_file = open('road_network.txt', 'r', encoding = 'UTF-8')
info = road_network_file.readline()
for line in road_network_file:
temp = line.split()
temp_dic_network = {int(temp[0]): ((int(temp[1]), int(temp[2]), int(temp[3]),
float(temp[4])))}
road_network.update(temp_dic_network) # (Edge ID, From Node ID, To

Node ID, Two Way, Speed (m/s))
for i in range(int(temp[5])):
temp_num_lati = float(re.sub('[^-.0-9]', '', temp[(i * 2 + 1) + 6])) #
Latitude
temp_num_longi = float(re.sub('[^-.0-9]', '', temp[(i * 2) + 6])) #
Longitude
# [Road Map]
if((round(temp_num_lati, DECIMAL), round(temp_num_longi, DECIMAL))
not in road_map):
temp_dic_map = {(round(temp_num_lati, DECIMAL),
round(temp_num_longi, DECIMAL)): [(int(temp[0]), i, temp_num_lati,
temp_num_longi)]}
road_map.update(temp_dic_map)
else:
road_map.get((round(temp_num_lati, DECIMAL),
round(temp_num_longi, DECIMAL))).append([int(temp[0]), i, temp_num_lati,
temp_num_longi])
# [Road List]
road_list.append([int(temp[0]), i, temp_num_lati, temp_num_longi], 0)
print("Road segment (number): ", len(road_list))
road_network_file.close()
# [Ground true data]
ground_true_file = open('ground_truth_route.txt', 'r', encoding = 'UTF-8')
info = ground_true_file.readline() # (Edge ID, Traversed From to To)
for line in ground_true_file:
temp = line.split()
ground_true.append((int(temp[0]), temp[1]))
print("Ground true (number): ", len(ground_true))
ground_true_file.close()
print('Elapsed time = ', round(time.time() - tStart, 2))
# --- Analysising ---
print('Analysising...')

V = [{}]
path = {}
# Need valid HMM states
# Initialize base cases (t == 0)
for y in road_list:
# Search road map
for i in range(3):
for j in range(3):
if ((round(y[0], DECIMAL) + i, round(y[1], DECIMAL) + j) in road_map):
temp = road_map.get(round(y[0], DECIMAL) + i, round(y[1],
DECIMAL) + j)
'''
Set status and count propability
'''
prev = (0, 0)
for t in range(len(gps_data)):
if(t == 0):
prev = gps_data[t]
elif(spherical_distance(prev, gps_data[t]) > 2 * ALPHA):
'''
do something
'''
prev = gps_data[t]
'''
1. Removing points that are within 2 * Standard Deviation of the previous point
2. HMM Breaks
2.1 More than (200m)
2.2 Route more than great circle (2000m)
2.3 Vehicle speed 3x in route or more than 50 m/s
'''
# --- Evaluation ---

'''
print('Evaluation...')
'''

Python hmm

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