datareader.py

# -*- coding: utf-8 -*-
"""
Created on Sun Jul 07 15:56:56 2013

@author: dima
"""

import csv
import onedrive

def read_gps(gpsstr):
    """
    input gpsstr is [latstr, lonstr]
    """
    return onedrive.Gps(float(gpsstr[0]), float(gpsstr[1]))
    
def read_time(timestr):
    """
    this converts the time string in the input data to seconds since 
    0:00:00 1/1/2007 utc.  
    note that the time is not real;  see gpsdata/readme.txt for details
    
    we do this hack instead of using dateutil.parser because we don't need
    to allow for multiple formats/timezones and dateutil.parser is very slow.
    """
    return ((int(timestr[8:10])-1)*86400 + int(timestr[11:13])*3600 + 
            int(timestr[14:16])*60 + int(timestr[17:19]))

def read_data(datafile, count=False):
    """
    returns a list of time-ordered OneDrives gathered from the input datafile
    """

    drivedic = {}
    everything = csv.reader(datafile, delimiter='\t')
    
    for row in everything:
        drive_id = int(row[0])
        time = read_time(row[1])
        gps = read_gps(row[2:4])
        
        if not(drive_id in drivedic):
            drivedic[drive_id] = onedrive.OneDrive(drive_id)
        
        drivedic[drive_id].append_coord(onedrive.TimeGps(time, gps))
            
    drives = drivedic.values()
    drives.sort(key=lambda d: d.coords[0].time)
    
    if count:
        return drives[:count]
    return drives