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#!/usr/bin/env python
#
# Analyze one or more NMEA or JSON files to determine the cycle sequence of
# sentences. JSON files must have been emitted by a driver without the
# CYCLE_END_RELIABLE capability, otherwise the results will be meaningless.
import sys, getopt, json
verbose = 0
class analyze_error:
def __init__(self, filename, lineno, msg):
self.filename = filename
self.lineno = lineno
self.msg = msg
def str(self):
return '"%s", line %d: %s' % (filename, lineno, msg)
def extract_from_nmea(filename, lineno, line):
"Extend sequence of tag/timestamp tuples from an NMEA sentence"
hhmmss = {
"$GPRMC": 1,
"$GPGLL": 5,
"$GPGGA": 1,
"$GPGBS": 1,
"$GPZDA": 1,
"$PASHR": 4,
}
fields = line.split(",")
tag = fields[0][1:]
if fields[0] in hhmmss:
timestamp = fields[hhmmss[fields[0]]]
return [(tag, timestamp)]
else:
return []
def extract_from_json(filename, lineno, line):
"Extend sequence of tag/timestamp tuples from a JSON dump of a sentence"
# FIXME: Analyze JSON sentences
raise analyze_error(filename, lineno, "JSON analsis not yet implemented.")
def extract_timestamped_sentences(fp):
"Do the basic work of extracting tags and timestamps"
sequence = []
filetype = None
lineno = 0
while True:
line = fp.readline()
if not line:
break
lineno += 1
if line.startswith("#"):
continue
elif filetype == None:
if line.startswith("$"):
filetype = "NMEA"
elif line.startswith("{"):
filetype = "JSON"
else:
raise analyze_error(fp.name, lineno, "unknown file type.")
if verbose:
print "cycle_analyzer: %s is %s" % (fp.name, filetype)
# The reason for this odd logic is that we want to oock onto
# either (a) analyzing NMEA only, or (b) analyzing JSON only
# and ignoring NMEA, depending on which kind the first data
# line of the file is. This gives the ability to run against
# either raw NMEA or regression-test .chk files generated by
# binary-format devices, without haviong to run gpsd to
# do reanalysis.
if filetype == "NMEA" and line.startswith("$"):
sequence += extract_from_nmea(fp.name, lineno, line)
elif filetype == "JSON" and line.startswith("{"):
sequence + extract_from_json(fp.name, lineno, line)
else:
sys.stderr.write("cycle_analyzer: non-NMEA, non-JSON data %s.\n" % line)
return []
return sequence
def analyze(fp, stage):
"Analyze the cycle sequence of a device from its output logs."
# First, extract tags and timestamps
sequence = extract_timestamped_sentences(fp)
if stage == "extract":
for (tag, timestamp) in sequence:
print "%s: %s" % (tag, timestamp)
# Then, do cycle detection
events = []
out_of_order = False
for i in range(len(sequence)-1):
(this_tag, this_time) = sequence[i]
(next_tag, next_time) = sequence[i+1]
if float(this_time) == 0:
continue
events.append(this_tag)
if float(this_time) < float(next_time):
events.append("-")
if float(this_time) < float(next_time):
out_of_order = True
if out_of_order:
sys.stderr.write("cycle_analyzer: some timestamps occur out of order in %s\n" % fp.name)
# We need 6 cycles because the first and last might be incomplete, and we
# need at least 4 cycles in the middle to have two full ones om
# split-cycle devices like old Garmins.
if events.count("-") < 6:
sys.stderr.write("cycle_analyzer: fewer than 5 cycles in\n" % fp.name)
if stage == "events":
for event in events:
print event
# Now group events into bursts
bursts = []
current = []
for event in events + ['-']:
if event == '-':
bursts.append(tuple(current))
current = []
else:
current.append(event)
if stage == "bursts":
for burst in bursts:
print burst
# FIXME: more analysis goes here
if __name__ == "__main__":
stage = None
try:
(options, arguments) = getopt.getopt(sys.argv[1:], "s:v")
for (switch, val) in options:
if (switch == '-s'):
stage = val # Stop at specicified stage
elif (switch == '-v'):
verbose += 1
except getopt.GetoptError, msg:
print "cycle_analyzer: " + str(msg)
raise SystemExit, 1
try:
if arguments:
for filename in arguments:
fp = open(filename)
analyze(fp, stage)
fp.close()
else:
analyze(sys.stdin)
except analyze_error, e:
print e
raise SystemExit, 1
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