Move buffer time to the utils function

Also adds documentation for buffer_time

tupak/gw/detector.py

@@ -233,6 +233,9 @@ class InterferometerStrainData(object):
             The data duration (in s)
         start_time: float
             The GPS start-time of the data
+        buffer_time: float
+            Read in data with `start_time-buffer_time` and
+            `start_time+duration+buffer_time`
 
         """
 
@@ -243,8 +246,8 @@ class InterferometerStrainData(object):
 
         logging.info('Reading data from frame')
         strain = tupak.gw.utils.read_frame_file(
-            frame_file, t1=start_time-buffer_time,
-            t2=start_time+duration+buffer_time, channel=channel_name,
+            frame_file, t1=start_time, t2=start_time+duration,
+            buffer_time=buffer_time, channel=channel_name,
             resample=sampling_frequency)
 
         frequency_domain_strain, frequencies = tupak.gw.utils.process_strain_data(strain, **kwargs)

tupak/gw/utils.py

@@ -336,7 +336,7 @@ def get_open_strain_data(
     return strain
 
 
-def read_frame_file(file_name, t1, t2, channel=None, **kwargs):
+def read_frame_file(file_name, t1, t2, channel=None, buffer_time=1, **kwargs):
     """ A function which accesses the open strain data
 
     This uses `gwpy` to download the open data and then saves a cached copy for
@@ -348,6 +348,8 @@ def read_frame_file(file_name, t1, t2, channel=None, **kwargs):
         The name of the frame to read
     t1, t2: float
         The GPS time of the start and end of the data
+    buffer_time: float
+        Read in data with `t1-buffer_time` and `t2+buffer_time`
     channel: str
         The name of the channel being searched for, some standard channel names are attempted
         if channel is not specified or if specified channel is not found.
@@ -374,7 +376,7 @@ def read_frame_file(file_name, t1, t2, channel=None, **kwargs):
             if loaded:
                 continue
             try:
-                strain = TimeSeries.read(source=file_name, channel=channel, start=t1, end=t2, **kwargs)
+                strain = TimeSeries.read(source=file_name, channel=channel, start=t1-buffer_time, end=t2+buffer_time, **kwargs)
                 loaded = True
                 logging.info('Successfully loaded {}.'.format(channel))
             except RuntimeError: