source: OpenWorkouts-current/ow/utilities.py @ 119412d

import re
from datetime import datetime
from decimal import Decimal
from shutil import copyfileobj

from unidecode import unidecode
from xml.dom import minidom
from ZODB.blob import Blob


def slugify(text, delim=u'-'):
    """
    Generates an ASCII-only slug.
    from http://flask.pocoo.org/snippets/5/
    """
    _punct_re = re.compile(r'[\t !"#$%&\'()*\-/<=>?@\[\\\]^_`{|},.]+')
    result = []
    text = unidecode(text)
    for word in _punct_re.split(text.lower()):
        result.extend(word.split())
    return delim.join(result)


class GPXMinidomParser(object):
    """
    GPX parser, using minidom from the base library.

    We need this as a workaround, as gpxpy does not handle GPX 1.1 extensions
    correctly right now (and we have not been able to fix it).

    This method is inspired by this blog post:

    http://castfortwo.blogspot.com.au/2014/06/
    parsing-strava-gpx-file-with-python.html
    """

    def __init__(self, gpx_path):
        self.gpx_path = gpx_path
        self.gpx = None
        self.tracks = {}

    def load_gpx(self):
        """
        Load the given gpx file into a minidom doc, normalize it and set
        self.gpx to the document root so we can reuse it later on
        """
        doc = minidom.parse(self.gpx_path)
        doc.normalize()
        self.gpx = doc.documentElement

    def parse_tracks(self):
        """
        Loop over all the tracks found in the gpx, parsing them
        """
        for trk in self.gpx.getElementsByTagName('trk'):
            self.parse_track(trk)

    def parse_track(self, trk):
        """
        Parse the given track, extracting all the information and putting it
        into a dict where the key is the track name and the value is a list
        of data for the the different segments and points in the track.

        All the data is saved in self.tracks
        """
        name = trk.getElementsByTagName('name')[0].firstChild.data
        if name not in self.tracks:
            self.tracks[name] = []

        for trkseg in trk.getElementsByTagName('trkseg'):
            for trkpt in trkseg.getElementsByTagName('trkpt'):
                lat = Decimal(trkpt.getAttribute('lat'))
                lon = Decimal(trkpt.getAttribute('lon'))

                # There could happen there is no elevation data
                ele = trkpt.getElementsByTagName('ele')
                if ele:
                    ele = Decimal(ele[0].firstChild.data)
                else:
                    ele = None

                rfc3339 = trkpt.getElementsByTagName('time')[0].firstChild.data
                try:
                    t = datetime.strptime(
                        rfc3339, '%Y-%m-%dT%H:%M:%S.%fZ')
                except ValueError:
                    t = datetime.strptime(
                        rfc3339, '%Y-%m-%dT%H:%M:%SZ')

                hr = None
                cad = None
                atemp = None
                extensions = trkpt.getElementsByTagName('extensions')
                if extensions:
                    extensions = extensions[0]
                    trkPtExt = extensions.getElementsByTagName(
                        'gpxtpx:TrackPointExtension')[0]
                    if trkPtExt:
                        hr_ext = trkPtExt.getElementsByTagName('gpxtpx:hr')
                        cad_ext = trkPtExt.getElementsByTagName('gpxtpx:cad')
                        atemp_ext = trkPtExt.getElementsByTagName(
                            'gpxtpx:atemp')
                        if hr_ext:
                            hr = Decimal(hr_ext[0].firstChild.data)
                        if cad_ext:
                            cad = Decimal(cad_ext[0].firstChild.data)
                        if atemp_ext:
                            atemp = Decimal(atemp_ext[0].firstChild.data)

                self.tracks[name].append({
                    'lat': lat,
                    'lon': lon,
                    'ele': ele,
                    'time': t,
                    'hr': hr,
                    'cad': cad,
                    'atemp': atemp})


def semicircles_to_degrees(semicircles):
    return semicircles * (180 / pow(2, 31))


def degrees_to_semicircles(degrees):
    return degrees * (pow(2, 31) / 180)


def miles_to_kms(miles):
    factor = 0.62137119
    return miles / factor


def kms_to_miles(kms):
    factor = 0.62137119
    return kms * factor


def meters_to_kms(meters):
    return meters / 1000


def kms_to_meters(kms):
    return kms * 1000


def mps_to_kmph(mps):
    """
    Transform a value from meters-per-second to kilometers-per-hour
    """
    return mps * 3.6


def kmph_to_mps(kmph):
    """
    Transform a value from kilometers-per-hour to meters-per-second
    """
    return kmph * 0.277778


def copy_blob(blob):
    """
    Create a copy of a blob object, returning another blob object that is
    the copy of the given blob file.
    """
    new_blob = Blob()
    if getattr(blob, 'file_extension', None):
        new_blob.file_extension = blob.file_extension
    with blob.open('r') as orig_blob, new_blob.open('w') as dest_blob:
        orig_blob.seek(0)
        copyfileobj(orig_blob, dest_blob)
    return new_blob


def create_blob(data, file_extension, binary=False):
    """
    Create a ZODB blob file from some data, return the blob object
    """
    blob = Blob()
    blob.file_extension = file_extension
    with blob.open('w') as open_blob:
        # use .encode() to convert the string to bytes if needed
        if not binary and not isinstance(data, bytes):
            data = data.encode('utf-8')
        open_blob.write(data)
    return blob