def _retrieve_metadata(stream, channel_name):
"""Retrieve basic metadata by reading the first file in the cache
Parameters
----------
stream: lal stream object
Stream containing a channel we want to learn about
channel_name: str
The name of the channel we want to know the dtype and sample rate of
Returns
-------
channel_type: lal type enum
Enum value which indicates the dtype of the channel
sample_rate: int
The sample rate of the data within this channel
"""
lalframe.FrStreamGetVectorLength(channel_name, stream)
channel_type = lalframe.FrStreamGetTimeSeriesType(channel_name, stream)
create_series_func = _fr_type_map[channel_type][2]
get_series_metadata_func = _fr_type_map[channel_type][3]
series = create_series_func(channel_name, stream.epoch, 0, 0,
lal.ADCCountUnit, 0)
get_series_metadata_func(series, stream)
return channel_type, int(1.0/series.deltaT)
def _read_channel(channel, stream, start, duration):
channel_type = lalframe.FrStreamGetTimeSeriesType(channel, stream)
read_func = _fr_type_map[channel_type][0]
d_type = _fr_type_map[channel_type][1]
data = read_func(stream, channel, start, duration, 0)
return TimeSeries(data.data.data, delta_t=data.deltaT, epoch=start,
dtype=d_type)
def _read_channel(stream, channel, start, duration):
dtype = lalframe.FrStreamGetTimeSeriesType(channel, stream)
reader = lalutils.find_typed_function(dtype,
'FrStreamRead',
'TimeSeries',
module=lalframe)
return reader(stream, channel, start, duration, 0)
def _read_channel(stream, channel, start, duration):
try:
dtype = lalframe.FrStreamGetTimeSeriesType(channel, stream)
except RuntimeError as exc:
if str(exc).lower() == "wrong name":
exc.args = "channel '{}' not found".format(channel),
raise
reader = lalutils.find_typed_function(dtype, 'FrStreamRead', 'TimeSeries',
module=lalframe)
return reader(stream, channel, start, duration, 0)
def read_frame(location, channels, start_time=None,
end_time=None, duration=None, check_integrity=True):
"""Read time series from frame data.
Using the `location`, which can either be a frame file ".gwf" or a
frame cache ".gwf", read in the data for the given channel(s) and output
as a TimeSeries or list of TimeSeries.
Parameters
----------
location : string
A source of gravitational wave frames. Either a frame filename
(can include pattern), a list of frame files, or frame cache file.
channels : string or list of strings
Either a string that contains the channel name or a list of channel
name strings.
start_time : {None, LIGOTimeGPS}, optional
The gps start time of the time series. Defaults to reading from the
beginning of the available frame(s).
end_time : {None, LIGOTimeGPS}, optional
The gps end time of the time series. Defaults to the end of the frame.
Note, this argument is incompatible with `duration`.
duration : {None, float}, optional
The amount of data to read in seconds. Note, this argument is
incompatible with `end`.
check_integrity : {True, bool}, optional
Test the frame files for internal integrity.
Returns
-------
Frame Data: TimeSeries or list of TimeSeries
A TimeSeries or a list of TimeSeries, corresponding to the data from
the frame file/cache for a given channel or channels.
"""
if end_time and duration:
raise ValueError("end time and duration are mutually exclusive")
if type(location) is list:
locations = location
else:
locations = [location]
cum_cache = locations_to_cache(locations)
stream = lalframe.FrStreamCacheOpen(cum_cache)
stream.mode = lalframe.FR_STREAM_VERBOSE_MODE
if check_integrity:
stream.mode = (stream.mode | lalframe.FR_STREAM_CHECKSUM_MODE)
lalframe.FrSetMode(stream.mode, stream)
# determine duration of data
if type(channels) is list:
first_channel = channels[0]
else:
first_channel = channels
data_length = lalframe.FrStreamGetVectorLength(first_channel, stream)
channel_type = lalframe.FrStreamGetTimeSeriesType(first_channel, stream)
create_series_func = _fr_type_map[channel_type][2]
get_series_metadata_func = _fr_type_map[channel_type][3]
series = create_series_func(first_channel, stream.epoch, 0, 0,
lal.ADCCountUnit, 0)
get_series_metadata_func(series, stream)
data_duration = data_length * series.deltaT
if start_time is None:
start_time = stream.epoch*1
if end_time is None:
end_time = start_time + data_duration
if type(start_time) is not lal.LIGOTimeGPS:
start_time = lal.LIGOTimeGPS(start_time)
if type(end_time) is not lal.LIGOTimeGPS:
end_time = lal.LIGOTimeGPS(end_time)
if duration is None:
duration = float(end_time - start_time)
else:
duration = float(duration)
# lalframe behaves dangerously with invalid duration so catch it here
if duration <= 0:
raise ValueError("Negative or null duration")
#if duration > data_duration:
# raise ValueError("Requested duration longer than available data")
if type(channels) is list:
all_data = []
for channel in channels:
channel_data = _read_channel(channel, stream, start_time, duration)
lalframe.FrStreamSeek(stream, start_time)
all_data.append(channel_data)
return all_data
else:
return _read_channel(channels, stream, start_time, duration)
def _read_channel(stream, channel, start, duration):
dtype = lalframe.FrStreamGetTimeSeriesType(channel, stream)
typestr = lalutils.LAL_TYPE_STR[dtype]
reader = getattr(lalframe, 'FrStreamRead%sTimeSeries' % typestr)
return reader(stream, channel, start, duration, 0)