# 4.6.2.2.3. eqcorrscan.core.lag_calc._prepare_data

`eqcorrscan.core.lag_calc.``_prepare_data`(detect_data, detections, template, delays, shift_len, plot)

  Prepare data for lag_calc - reduce memory here.

  Parameters: | detect_data (obspy.core.stream.Stream) Stream to extract detection streams from. detections (list) List of `eqcorrscan.core.match_filter.Detection` to get data for. template (tuple) tuple of (template_name, template) delays (list) Dictionary of delay times in seconds keyed by sta.channel. shift_len (float) Shift length in seconds allowed for picking. plot (bool) Whether to plot the data extracted or not, used for debugging.
  Returns: | List of detect_streams to be worked on
  Return type: | list