# 5.4.1.4. eqcorrscan.utils.clustering.corr_cluster

`eqcorrscan.utils.clustering.``corr_cluster`(trace_list, thresh=0.9)

  Group traces based on correlations above threshold with the stack.

  Will run twice, once with a lower threshold to remove large outliers that would negatively affect the stack, then again with your threshold.

  Parameters: | trace_list (list) List of `obspy.core.stream.Trace` to compute similarity between thresh (float) Correlation threshold between -1-1
  Returns: | `numpy.ndarray` of bool of whether that trace correlates well enough (above your given threshold) with the stack.

  Note

  We recommend that you align the data before computing the clustering, e.g., the P-arrival on all templates for the same channel should appear at the same time in the trace. See the `eqcorrscan.utils.stacking.align_traces()` function for a way to do this.