skip writing timeseries if channel not in request channels

geomagio/covjson/CovJSONFactory.py

@@ -249,6 +249,8 @@ class CovJSONFactory(TimeseriesFactory):
 
         for trace in timeseries:
             ch_name = trace.stats.channel
+            if channels and ch_name not in channels:
+                continue
             element_info = ELEMENT_INDEX.get(ch_name)
             if element_info:
                 param_description = element_info.name