Read JWD and plot time

To plot time in file along x-axis i changed
import numpy as np
from DropSizeDistribution import DropSizeDistribution
import datetime
import pandas as pd
UTC_OFFSET_TIMEDELTA = datetime.timedelta(0, 19800) # 5 X 3600 + 30 X 60 Indian time offset used to convert time in IST to UTC.

def read_jwd_utc(filename):
'''
Takes a filename pointing to a Joss-WaldVogel file and returns
a drop size distribution object.

Usage:
dsd = read_jwd(filename)

Returns:
DropSizeDistrometer object

'''

reader = JWDReader_utc(filename)
dsd = DropSizeDistribution(reader.time, reader.Nd, spread=reader.spread,
                           diameter=reader.diameter, rain_rate=reader.rain_rate,
                           bin_edges=reader.bin_edges)
return dsd

class JWDReader_utc(object):

'''
JWDReader class takes takes a filename as it's only argument(for now).
This should be a Joss-Waldvogel datafile.
'''
diameter = np.array([
    0.359, 0.455, 0.551, 0.656, 0.771, 0.913, 1.116, 1.331, 1.506, 1.665,
    1.912, 2.259, 2.584, 2.869, 3.198, 3.544, 3.916, 4.350, 4.859, 5.373])

spread = np.array([
    0.092, 0.100, 0.091, 0.119, 0.112, 0.172, 0.233, 0.197, 0.153, 0.166,
    0.329, 0.364, 0.286, 0.284, 0.374, 0.319, 0.423, 0.446, 0.572, 0.455])

def __init__(self, filename):
    self.filename = filename
    self.rain_rate = []

    self.Nd = []
    self.time = []

    self._read_file()
    self._prep_data()

    self.bin_edges = np.hstack(
        (0, self.diameter + np.array(self.spread) / 2))



def conv_md_to_nd(self, Nd):
    F = 0.005
    t = 30.0
    v = 9.65 - 10.3 * np.exp(-0.6 * self.diameter)
    return np.divide(Nd, (F * t * np.multiply(v, self.spread)))

def _read_file(self):
    with open(self.filename) as f:
        next(f)
        for i,line in enumerate(f):
            self.time.append(datetime.datetime.strptime((line.split('\t')[0]+line.split('\t')[1]),'%Y-%m-%d%H:%M:%S')-UTC_OFFSET_TIMEDELTA)



def _prep_data(self):
    self.Nd = np.array(self.Nd)
    self.time = pd.Series(np.array(self.time))
    #self.time = self.time - self.time[0]
    self.rain_rate = np.array(self.rain_rate)