下载EU台网（欧洲台网）的地震波数据

### here first to check the existence of the focal mechanism event file in the NDK directory,
###  if existence, mostly useful for the waveforms inversion,if not,download the event quakeml from
###  iris without focal mechanism. Then download the data from IRIS and GFZ, and before run, should 
###  update the username and password for the restricted data.
###  http://geofon.gfz-potsdam.de/waveform/archive/auth/auth-example.php
###  wget --post-file /data2/yjgao/token.asc https://geofon.gfz-potsdam.de/fdsnws/dataselect/1/auth -O cred.txt
###  Yajian Gao, 2017,12,26,GFZ

from obspy import read_events
from obspy.clients.fdsn import Client
from obspy import UTCDateTime
import os
import sys
import datetime
import obspy
from pathlib import Path
import os.path
from obspy.clients.fdsn.mass_downloader import CircularDomain,     Restrictions, MassDownloader
from obspy.clients.seedlink.easyseedlink import create_client
#def handle_data(trace):
    #print(‘Received the following trace:‘)
    #print(trace)
    #print()
#client = create_client(‘geofon.gfz-potsdam.de‘, on_data=handle_data)
client = Client("IRIS")
if len(sys.argv) != 8:
    sys.exit("Usage: python %s year month day hour:minute:seconds eventid evla evlo"% sys.argv[0])
year,month,day,origin,eventid,evla,evlo = sys.argv[1:]
hour,minute,second=origin.split(‘:‘)
#############################################download quakeml from IRIS without FOCAL MECHANISM

EVENTFILENAME=‘C‘+str(year)+str(month)+str(day)+str(hour)+str(minute)+‘A.ndk‘
PATH="../NDK/"+str(EVENTFILENAME)
print(PATH)
ts=os.path.exists(PATH)
if ts== True:
    print(ts)
    cat = obspy.read_events("../NDK/"+str(EVENTFILENAME))
    print(cat)