climb_rate.py

"""
Plot climb rate (in vertical ft/min) against grade. Break it up in 10-point
chunks?
"""

from datetime import datetime
from xml.dom.minidom import parse


def grouper(n, iterable):
    """
    Return elements from iterable n items at a time.
    e.g. grouper(3,[1,2,3,4,5,6,7]) -> ([1,2,3], [4,5,6], [7])
    """
    iterable = iter(iterable)
    ret = []
    for item in iterable:
        ret.append(item)
        if len(ret) >= n:
            yield ret
            ret = []
    if len(ret) > 0:
        yield ret


def grab(el, field):
    return el.getElementsByTagName(field)[0].childNodes[0].data


def parse():
    root = parse('Geneva-Nice Profile.tcx')

    def parse_trackpoint(el):
        time_str = grab(el, 'Time')
        print "time_str is %r" % time_str
        time = datetime.strptime(time_str, "%Y-%m-%dT%H:%M:%SZ")
        dist = float(grab(el, 'DistanceMeters'))
        alt = float(grab(el, 'AltitudeMeters'))
        return (time, dist, alt)

    def parse_activity(el):
        rates = []
        first = None
        for points in grouper(10, el.getElementsByTagName('Trackpoint')):
            last = parse_trackpoint(points[-1])
            if first:
                dist = last[1] - first[1]
                # grade in %
                if dist > 0:
                    grade = 100. * ((last[2] - first[2]) / dist)
                    td = last[0] - first[0]
                    time_secs = td.seconds + (td.days * 24 * 3600)
                    if time_secs > 0:
                        # meters / second
                        climb_rate = (last[2] - first[2]) / time_secs
                        # ft / hour
                        climb_rate = (climb_rate * 3.3 * 60 * 60)
                        print "initial time is %r" % first[0]
                        print "final time is %r" % last[0]
                        print "time_secs is %0.2f" % time_secs
                        print "altitude diff is %f" % (last[2] - first[2])
                        print "climb_rate is %f" % climb_rate
                        rates.append((climb_rate, grade))
            first = last
        return rates

    # Need to sort these by Id.
    climb_rates = []
    for activity in root.getElementsByTagName('Activity'):
        climb_rates.extend(parse_activity(activity))

    return climb_rates


if __name__ == '__main__':
    data = [(rate, grade) for rate, grade in parse()
            if 0 < grade < 20)]
    with open('out.csv', 'w') as f:
        for rate, grade in data:
            f.write('%f,%f\n' % (grade, rate))