Fluxtream BodyTrack HR status

bodytrack.py

#!/usr/bin/python

import time
import httplib
import base64
import math
import json

# this script gets the latest HR data (within the past 5 minutes)
# from fluxtream's body track API.

# replace the below strings with your credentials
USERNAME = 'username'
PASSWORD = 'password'


#    /api/guest
#    #   curl -u test:testtest http://fluxtream.org/api/guest
#        {
#            "username":"test",
#            "firstname":"test",
#            "lastname":"test",
#            "email":"[email protected]",
#            "roles":"[role_user]",
#            "id":1
#        }
#
#    /api/bodytrack/tiles/uid/devicenickname.channelname/level.offset.json
#      curl -u test:testtest http://flxtest.bodytrack.org/api/bodytrack/tiles/1/polarstrap.beatspacing/5.82564.json
#    returns
#    {
#       "fields":["time","mean","stddev","count"],
#       "data":[
#                   [1352729398.800067,0.966,1.485415458679199,15],
#                   [1352729423.768154,0.6116538461538461,0.04332740977406502,52],
#                    ...
#                   [1352743298.36375,0.51925,0.1960801780223846,8],
#                   [1352744129.181875,-1e+308,0,0]
#                 ],
#       "level":5,
#       "offset":82564,
#       "sample_width":32,
#       "type":"value"
#    }

# for example, at level 5 each bin is 2^5 or 32 seconds.  there are 512 bins per tile, so duration = 32*512=16384 seconds. 
# the offset of the tile containing the t = 1384776000 is offset = 1384776000/16384, rounded down to the nearest integer, which is 84520. 


def main():
    connection = httplib.HTTPConnection('fluxtream.org')
    auth = base64.encodestring(USERNAME+":"+PASSWORD).decode("ascii")
    headers = {'Authorization': 'Basic %s' % auth}

    user_id = login(connection, headers)
    recent_hr = hr_data(connection, headers, user_id)
    recent_hrv_stddev = hrv_data(connection, headers, user_id)
    connection.close()

    display_response = ['n/a', 'n/a']

    #print('recent heart rate: ' + str(recent_hr))
    # return the HR value (if acceptable), 'N/A' otherwise
    if recent_hr > 0 and recent_hr < 230:
        display_response[0] = str(int(recent_hr)) + ' bpm'
    if recent_hrv_stddev > 0:
        display_response[1] = "{:.1f}".format(recent_hrv_stddev) + ' ms'

    return "\n".join(display_response)


def login(connection, headers):
    url = '/api/guest'
    connection.request('GET', url, headers=headers)
    response = connection.getresponse()
    if response.status != 200:
        return -1

    response_data = json.loads(response.read())
    #print('login response: ' + str(response_data))

    user_id = response_data['id']
    return user_id


def hr_data(connection, headers, user_id):
    # user_id, level.offset
    level = -1  # bin_width is 2^level seconds wide (2^5 = 32 seconds, 2^-1 = 0.5 seconds)
    tile_width = 2**level * 512
    desired_time = time.time()
    offset = int(math.floor(desired_time / tile_width))

    last_hr = -1

    # try to load (up to) two tiles (sometimes the "current" tile is empty)
    # this means that we could be showing data potentially 2*tile_width seconds out-of-date
    for i in range(2):
        url = '/api/bodytrack/tiles/%s/PolarStrap.HeartRate/%s.%s.json' % (user_id, level, offset-i)
        #print('hr url: ' +url)
        connection.request('GET', url, headers=headers)
        response = connection.getresponse()

        if response.status != 200:
            return -1

        response_data = json.loads(response.read())
        #print('hr response: ' + str(response_data))

        mean_index = response_data['fields'].index('mean')
        if mean_index < 0:
            return -1

        for sample in reversed(response_data['data']):
            hr_value = sample[mean_index]
            if hr_value > 0 and hr_value < 230:
                last_hr = hr_value
                break

        # if we have found a valid hr sample then stop any additional requests
        if last_hr > 0:
            break

    return last_hr


def hrv_data(connection, headers, user_id):
    # user_id, level.offset
    level = 8  # bin_width is 2^level seconds wide (2^5 = 32 seconds, 2^-1 = 0.5 seconds)
    tile_width = 2**level * 512
    desired_time = time.time()
    offset = int(math.floor(desired_time / tile_width))

    last_hrv = -1

    # try to load (up to) two tiles (sometimes the "current" tile is empty)
    # this means that we could be showing data potentially 2*tile_width seconds out-of-date
    for i in range(2):
        url = '/api/bodytrack/tiles/%s/PolarStrap.BeatSpacing/%s.%s.json' % (user_id, level, offset-i)
        #print('hr url: ' +url)
        connection.request('GET', url, headers=headers)
        response = connection.getresponse()

        if response.status != 200:
            return -1

        response_data = json.loads(response.read())
        #print('hr response: ' + str(response_data))

        stddev_index = response_data['fields'].index('stddev')
        if stddev_index < 0:
            return -1

        # lop off the tail, which is usually an incomplete|empty bin.
        for sample in reversed(response_data['data'][:-2]):
            hrv = sample[stddev_index]
            if hrv > 0:
                last_hrv = hrv
                break

        # if we have found a sample then stop any additional requests
        if last_hrv > 0:
            break

    return last_hrv * 1000  # unit seem to be seconds...want milliseconds


if __name__ == '__main__':
    result = main()
    print result