# 5.2.1.5. eqcorrscan.utils.catalog_to_dd.write_correlations

`eqcorrscan.utils.catalog_to_dd.``write_correlations`(event_list, wavbase, extract_len, pre_pick, shift_len, lowcut=1.0, highcut=10.0, max_sep=8, min_link=8, cc_thresh=0.0, plotvar=False, debug=0)

  Write a dt.cc file for hypoDD input for a given list of events.

  Takes an input list of events and computes pick refinements by correlation. Outputs two files, dt.cc and dt.cc2, each provides a different weight, dt.cc uses weights of the cross-correlation, and dt.cc2 provides weights as the square of the cross-correlation.

  Parameters: | event_list (list) List of tuples of event_id (int) and sfile (String) wavbase (str) Path to the seisan wave directory that the wavefiles in the S-files are stored extract_len (float) Length in seconds to extract around the pick pre_pick (float) Time before the pick to start the correlation window shift_len (float) Time to allow pick to vary lowcut (float) Lowcut in Hz - default=1.0 highcut (float) Highcut in Hz - default=10.0 max_sep (float) Maximum separation between event pairs in km min_link (int) Minimum links for an event to be paired cc_thresh (float) Threshold to include cross-correlation results. plotvar (bool) To show the pick-correction plots, defualts to False. debug (int) Variable debug levels from 0-5, higher=more output.

  Warning

  This is not a fast routine!

  Warning

  In contrast to seisan’s corr routine, but in accordance with the hypoDD manual, this outputs corrected differential time.

  Note

  Currently we have not implemented a method for taking unassociated event objects and wavefiles. As such if you have events with associated wavefiles you are advised to generate Sfiles for each event using the sfile_util module prior to this step.

  Note

  There is no provision to taper waveforms within these functions, if you desire this functionality, you should apply the taper before calling this. Note the `obspy.Trace.taper()` functions.