Check for spikes and raise error if found.

eqcorrscan/core/match_filter.py

@@ -3758,7 +3758,7 @@ def match_filter(template_names, template_list, st, threshold,
                     raise MatchFilterError(
                         'Template sampling rate does not '
                         'match continuous data')
-
+    _spike_test(st, 0.99, 1e6)
     # Copy the stream here because we will muck about with it
     stream = st.copy()
     templates = copy.deepcopy(template_list)
@@ -4023,6 +4023,31 @@ def match_filter(template_names, template_list, st, threshold,
         return detections, det_cat, detection_streams
 
 
+def _spike_test(stream, percent=0.99, multiplier=1e6):
+    """
+    Check for very large spikes in data and raise an error if found.
+
+    :param stream: Stream to look for spikes in.
+    :type stream: :class:`obspy.core.stream.Stream`
+    :param percent: Percentage as a decimal to calcualte range for.
+    :type percent: float
+    :param multiple: Multiplier of range to define a spike.
+    :type multiple: float
+    """
+    for tr in stream:
+        if (tr.data > 2 * np.max(
+            np.sort(np.abs(
+                tr))[0:int(percent * len(tr.data))]) * multiplier).sum() > 0:
+            msg = ('Spikes above ' + str(multiplier) +
+                   ' of the range of ' + str(percent) +
+                   ' of the data present, check. \n ' +
+                   'This would otherwise likely result in an issue during ' +
+                   'FFT prior to cross-correlation.\n' +
+                   'If you think this spike is real please report ' +
+                   'this as a bug.')
+            raise MatchFilterError(msg)
+
+
 if __name__ == "__main__":
     import doctest
     doctest.testmod()

eqcorrscan/tests/match_filter_test.py

@@ -23,7 +23,7 @@
 from eqcorrscan.core.match_filter import read_detections, get_catalog
 from eqcorrscan.core.match_filter import write_catalog, extract_from_stream
 from eqcorrscan.core.match_filter import Tribe, Template, Party, Family
-from eqcorrscan.core.match_filter import read_party, read_tribe
+from eqcorrscan.core.match_filter import read_party, read_tribe, _spike_test
 from eqcorrscan.tutorials.get_geonet_events import get_geonet_events
 from eqcorrscan.utils import pre_processing, catalog_utils
 
@@ -134,6 +134,13 @@ def test_failed_normxcorr(self):
         ccc = normxcorr2(template=[0, 1, 2, 3, 4], image='bob')
         self.assertEqual(ccc, 'NaN')
 
+    def test_spike_test(self):
+        """Check that an error is raised!"""
+        stream = read()
+        stream[0].data[100] = 1e20
+        with self.assertRaises(MatchFilterError):
+            _spike_test(stream)
+
 
 class TestSynthData(unittest.TestCase):
     def test_debug_range(self):