# 4.6.3.3.2. eqcorrscan.core.match_filter._group_detect

`eqcorrscan.core.match_filter.``_group_detect`(templates, stream, threshold, threshold_type, trig_int, plotvar, group_size=None, pre_processed=False, daylong=False, parallel_process=True, xcorr_func=None, concurrency=None, cores=None, ignore_length=False, overlap='calculate', debug=0)

  Pre-process and compute detections for a group of templates.

  Will process the stream object, so if running in a loop, you will want to copy the stream before passing it to this function.

  Parameters: | templates (list) List of `eqcorrscan.core.match_filter.Template` stream (obspy.core.stream.Stream) Continuous data to detect within using the Template. threshold (float) Threshold level, if using threshold_type=’MAD’ then this will be the multiple of the median absolute deviation. threshold_type (str) The type of threshold to be used, can be MAD, absolute or av_chan_corr. See Note on thresholding below. trig_int (float) Minimum gap between detections in seconds. If multiple detections occur within trig_int of one-another, the one with the highest cross-correlation sum will be selected. plotvar (bool) Turn plotting on or off, see warning about plotting below. group_size (int) Maximum number of templates to run at once, use to reduce memory consumption, if unset will use all templates. pre_processed (bool) Set to True if stream has already undergone processing, in this case eqcorrscan will only check that the sampling rate is correct. Defaults to False, which will use the `eqcorrscan.utils.pre_processing` routines to resample and filter the continuous data. daylong (bool) Set to True to use the `eqcorrscan.utils.pre_processing.dayproc()` routine, which preforms additional checks and is more efficient for day-long data over other methods. parallel_process (bool) xcorr_func (str or callable) A str of a registered xcorr function or a callable for implementing a custom xcorr function. For more details see: `eqcorrscan.utils.correlate.register_array_xcorr()` concurrency (str) The type of concurrency to apply to the xcorr function. Options are ‘multithread’, ‘multiprocess’, ‘concurrent’. For more details see `eqcorrscan.utils.correlate.get_stream_xcorr()` cores (int) Number of workers for processing and correlation. ignore_length (bool) If using daylong=True, then dayproc will try check that the data are there for at least 80% of the day, if you don’t want this check (which will raise an error if too much data are missing) then set ignore_length=True. This is not recommended! overlap (float) Either None, “calculate” or a float of number of seconds to overlap detection streams by. This is to counter the effects of the delay-and-stack in calcualting cross-correlation sums. Setting overlap = “calculate” will work out the appropriate overlap based on the maximum lags within templates. debug (int) Debug level from 0-5 where five is more output, for debug levels 4 and 5, detections will not be computed in parallel.
  Returns: | `eqcorrscan.core.match_filter.Party` of families of detections.