From ddbf4bd7df4b1a03e128bf2d86cdb7fa1344a85e Mon Sep 17 00:00:00 2001
From: Jeremy Fee <jmfee@usgs.gov>
Date: Fri, 20 May 2016 11:00:14 -0600
Subject: [PATCH] Add utilities for masking, unmasking, and merging streams
---
geomagio/TimeseriesUtility.py | 76 +++++++++++++++++++++++++++++++++++
1 file changed, 76 insertions(+)
diff --git a/geomagio/TimeseriesUtility.py b/geomagio/TimeseriesUtility.py
index e547e63c..1e9061c0 100644
--- a/geomagio/TimeseriesUtility.py
+++ b/geomagio/TimeseriesUtility.py
@@ -1,5 +1,6 @@
"""Timeseries Utilities"""
import numpy
+import obspy.core
def get_stream_gaps(stream):
@@ -129,3 +130,78 @@ def get_channels(stream):
if channel:
channels[channel] = True
return [ch for ch in channels]
+
+
+def mask_stream(stream):
+ """Convert stream traces to masked arrays.
+
+ Parameters
+ ----------
+ stream : obspy.core.Stream
+ stream to mask
+
+ Returns
+ -------
+ obspy.core.Stream
+ stream with new Trace objects with numpy masked array data.
+ """
+ masked = obspy.core.Stream()
+ for trace in stream:
+ masked += obspy.core.Trace(
+ numpy.ma.masked_invalid(trace.data),
+ trace.stats)
+ return masked
+
+
+def unmask_stream(stream):
+ """Convert stream traces to unmasked arrays.
+
+ Parameters
+ ----------
+ stream : obspy.core.Stream
+ stream to unmask
+
+ Returns
+ -------
+ obspy.core.Stream
+ stream with new Trace objects with numpy array data, with numpy.nan
+ as a fill value in a filled array.
+ """
+ unmasked = obspy.core.Stream()
+ for trace in stream:
+ unmasked += obspy.core.Trace(
+ trace.data.filled(fill_value=numpy.nan)
+ if isinstance(trace.data, numpy.ma.MaskedArray)
+ else trace.data,
+ trace.stats)
+ return unmasked
+
+
+def merge_streams(*streams):
+ """Merge one or more streams.
+
+ Parameters
+ ----------
+ *streams : obspy.core.Stream
+ one or more streams to merge
+
+ Returns
+ -------
+ obspy.core.Stream
+ stream with contiguous traces merged, and gaps filled with numpy.nan
+ """
+ merged = obspy.core.Stream()
+ # add unmasked, split traces to be merged
+ for stream in streams:
+ merged += mask_stream(stream)
+ # split traces that contain gaps
+ merged = merged.split()
+ # merge data
+ merged.merge(
+ # 1 = do not interpolate
+ interpolation_samples=1,
+ # 1 = when there is overlap, use data from trace with last endtime
+ method=1)
+ # convert back to NaN filled array
+ merged = unmask_stream(merged)
+ return merged
--
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