# Copyright (C) 2017 Alex Nitz
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 3 of the License, or (at your
# option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Generals
# Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
"""
This modules contains functions for getting data from the Gravitational Wave
Open Science Center (GWOSC).
"""
import logging
import json
from urllib.request import urlopen
from pycbc.io import get_file
from pycbc.frame import read_frame
logger = logging.getLogger('pycbc.frame.gwosc')
_GWOSC_URL = "https://www.gwosc.org/archive/links/%s/%s/%s/%s/json/"
[docs]def get_run(time, ifo=None):
"""Return the run name for a given time.
Parameters
----------
time: int
The GPS time.
ifo: str
The interferometer prefix string. Optional and normally unused,
except for some special times where data releases were made for a
single detector under unusual circumstances. For example, to get
the data around GW170608 in the Hanford detector.
"""
cases = [
(
# ifo is only needed in this special case, otherwise,
# the run name is the same for all ifos
1180911618 <= time <= 1180982427 and ifo == 'H1',
'BKGW170608_16KHZ_R1'
),
(1253977219 <= time <= 1320363336, 'O3b_16KHZ_R1'),
(1238166018 <= time <= 1253977218, 'O3a_16KHZ_R1'),
(1164556817 <= time <= 1187733618, 'O2_16KHZ_R1'),
(1126051217 <= time <= 1137254417, 'O1'),
(815011213 <= time <= 875318414, 'S5'),
(930787215 <= time <= 971568015, 'S6')
]
for condition, name in cases:
if condition:
return name
raise ValueError(f'Time {time} not available in a public dataset')
def _get_channel(time):
if time < 1164556817:
return 'LOSC-STRAIN'
return 'GWOSC-16KHZ_R1_STRAIN'
[docs]def gwosc_frame_json(ifo, start_time, end_time):
"""Get the information about the public data files in a duration of time.
Parameters
----------
ifo: str
The name of the interferometer to find the information about.
start_time: int
The start time in GPS seconds.
end_time: int
The end time in GPS seconds.
Returns
-------
info: dict
A dictionary containing information about the files that span the
requested times.
"""
run = get_run(start_time)
run2 = get_run(end_time)
if run != run2:
raise ValueError(
'Spanning multiple runs is not currently supported. '
f'You have requested data that uses both {run} and {run2}'
)
url = _GWOSC_URL % (run, ifo, int(start_time), int(end_time))
try:
return json.loads(urlopen(url).read().decode())
except Exception as exc:
msg = ('Failed to find gwf files for '
f'ifo={ifo}, run={run}, between {start_time}-{end_time}')
raise ValueError(msg) from exc
[docs]def gwosc_frame_urls(ifo, start_time, end_time):
"""Get a list of URLs to GWOSC frame files.
Parameters
----------
ifo: str
The name of the interferometer to find the information about.
start_time: int
The start time in GPS seconds.
end_time: int
The end time in GPS seconds.
Returns
-------
frame_files: list
A dictionary containing information about the files that span the
requested times.
"""
data = gwosc_frame_json(ifo, start_time, end_time)['strain']
return [d['url'] for d in data if d['format'] == 'gwf']
[docs]def read_frame_gwosc(channels, start_time, end_time):
"""Read channels from GWOSC data.
Parameters
----------
channels: str or list
The channel name to read or list of channel names.
start_time: int
The start time in GPS seconds.
end_time: int
The end time in GPS seconds.
Returns
-------
ts: TimeSeries
Returns a timeseries or list of timeseries with the requested data.
"""
if not isinstance(channels, list):
channels = [channels]
ifos = [c[0:2] for c in channels]
urls = {}
for ifo in ifos:
urls[ifo] = gwosc_frame_urls(ifo, start_time, end_time)
if len(urls[ifo]) == 0:
raise ValueError("No data found for %s so we "
"can't produce a time series" % ifo)
fnames = {ifo: [] for ifo in ifos}
for ifo in ifos:
for url in urls[ifo]:
fname = get_file(url, cache=True)
fnames[ifo].append(fname)
ts_list = [read_frame(fnames[channel[0:2]], channel,
start_time=start_time, end_time=end_time)
for channel in channels]
if len(ts_list) == 1:
return ts_list[0]
return ts_list
[docs]def read_strain_gwosc(ifo, start_time, end_time):
"""Get the strain data from the GWOSC data.
Parameters
----------
ifo: str
The name of the interferometer to read data for. Ex. 'H1', 'L1', 'V1'.
start_time: int
The start time in GPS seconds.
end_time: int
The end time in GPS seconds.
Returns
-------
ts: TimeSeries
Returns a timeseries with the strain data.
"""
channel = _get_channel(start_time)
return read_frame_gwosc(f'{ifo}:{channel}', start_time, end_time)