millisecs in GPX file format?

[aag]

The time/date stamps of the ANT+ HR monitor in the GPX files made by Orux have the format "2014-05-21T06:25:28Z". Does the GPX file format allow for recording milliseconds? If so, could you implement that? For accurately recording and processing HR data, milliseconds would be crucial.

[fabrylama]

The time/date stamps of the ANT+ HR monitor in the GPX files made by Orux have the format "2014-05-21T06:25:28Z". Does the GPX file format allow for recording milliseconds? If so, could you implement that? For accurately recording and processing HR data, milliseconds would be crucial.

Ant+ and bt sensors transmits a packet of data at most once a second, so it's useless to know exactly when the data was received, since the HR number orux get is just an average over 1 second calculated by the sensor itself.

[aag]

Ant+ and bt sensors transmits a packet of data at most once a second, so it's useless to know exactly when the data was received, since the HR number orux get is just an average over 1 second calculated by the sensor itself.

Oh really? Because here I am copying an excerpt from yesterday's GPX file, which clearly shows 5 or more ANT+ records per second (from a chest strap) . Hence there is no doubt that >1 packets/sec are received.



I am writing a Python script which does some interesting number-crunching on these data, which I shall be happy to post once it's functional.

Code Select Expand


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[aag]

this is a but of a quick hack, but it will extract and plot HR data from the Orux GPX files. I will improve it over time. The final goal is to gain functionality equivalent to PolarPro Trainer (histograms etc), but with the added location data.

Code Select Expand


import re
from string import Formatter
import time
import datetime
from time import strftime,strptime
from datetime import timedelta
import array
import matplotlib
from numpy  import *
import scipy
from pylab import *


#Equations for Determination of Calorie Burn if VO2max is Unknown
#Male: ((-55.0969 + (0.6309 x HR) + (0.1988 x W) + (0.2017 x A))/4.184) x 60 x T
#Female: ((-20.4022 + (0.4472 x HR) - (0.1263 x W) + (0.074 x A))/4.184) x 60 x T
#
#where
#
#HR = Heart rate (in beats/minute)
#W = Weight (in kilograms)
#A = Age (in years)
#T = Exercise duration time (in hours)


#______________________________________________________

def strfdelta(tdelta, fmt):
    f = Formatter()
    d = {}
    l = {'Y': 31536000, 'D': 86400, 'H': 3600, 'M': 60, 'S': 1}
    k = map( lambda x: x[1], list(f.parse(fmt)))
    rem = int(tdelta.total_seconds())

    for i in ('Y', 'D', 'H', 'M', 'S'):
        if i in k and i in l.keys():
            d[i], rem = divmod(rem, l[i])

    return f.format(fmt, **d)

#______________________________________________________
def getSec(s):
    l = s.split(':')
    return int(l[0]) * 3600 + int(l[1]) * 60 + int(l[2])

#______________________________________________________

# constants

HeartRates = open ("C:\Users\aag\Documents\Python\HeartRates.txt", "w")
gpxLinesList = [line.split(',') for line in open("C:\Users\aag\Documents\Python\test2.gpx")]
a= 0
previousHeartTime = 0
indexMultipleHR =0
indexGpx = 0
indexGpxHr =0
heartRateValue =0
weightAA = 92
birthdayAA = datetime.datetime(1960, 12, 1)
today = datetime.datetime.now()
ageAA = 53 # strfdelta(today - birthdayAA,"{Y}")
heartRateMatrix2D = []
heartRateMatrix3D = []
listHR = []
listHrTimeStamp = []
listHrInterval = []
#______________________________________________________

for eachLine in gpxLinesList:# iterate through each line of the GPX file
    indexGpx +=1
    matchHrLine = re.match(r"[[].d{1,}sd{4}[-]d{2}[-]d{2}[T]d{2}[:]d{2}[:]d{2}[Z]", str(eachLine))
    if matchHrLine: # if finds a line containing heart rate information
        indexGpxHr +=1
        heartTime = datetime.datetime.strptime(str(matchHrLine.group() [-20:-1]) , '%Y-%m-%dT%H:%M:%S')  # extract timestamp
        if previousHeartTime == 0 :
            oneSec = timedelta(seconds=1)
            previousHeartTime = heartTime-oneSec # for the 1st line, assume 1 second lag
        heartTimeInterval = int((heartTime - previousHeartTime).total_seconds()) # lag from previous measurememt
        matchHeartRate = re.search(r"[[].d{1,}s", str(matchHrLine.group())) # match heart rate
        heartRateValue = int(str(matchHeartRate.group()[2:])) # extract heart rate                  
        #print(indexGpx, indexGpxHr, heartTime, heartRateValue, previousHeartTime,  heartTimeInterval)
        previousHeartTime = heartTime
        heartRateLine = [heartRateValue, heartTime, heartTimeInterval]#
        heartRateMatrix2D.append(heartRateLine)
        #print (heartRateLine)
       
        listHR.append(heartRateValue) # now populate lists
        listHrTimeStamp.append(heartTime)
        listHrInterval.append(heartTimeInterval)
       
#print (heartRateMatrix2D)
arrayHR = asarray(listHR)
arrayHrTimeStamp = asarray(listHrTimeStamp)
print (ageAA, arrayHR, min(arrayHR), max(arrayHR), mean(arrayHR), std(arrayHR))
plot(arrayHrTimeStamp,arrayHR)
savefig("C:/Users/aag/Documents/Python/HrOverTime.png",dpi=144)
show()
# use of hist()
#  matplotlib.pyplot.hist(x, bins=10, range=None,
#       normed=False, weights=None, cumulative=False, bottom=None,
#       histtype='bar', align='mid', orientation='vertical', rwidth=None,
#       log=False, color=None, label=None, stacked=False, hold=None, **kwargs)

n, bins, patches = hist(arrayHR, 10, normed=1, histtype='stepfilled')
savefig("C:/Users/aag/Documents/Python/HrHistogram.png",dpi=144)
#setp(patches, 'facecolor', 'g', 'alpha', 0.75)

show()