Resolve "release v2.3.0"

Closes #440 (closed)

mlair/helpers/filter.py

@@ -118,7 +118,11 @@ class FIRFilter:
             filt = xr.apply_ufunc(fir_filter_convolve, d,
                                   input_core_dims=[[time_dim]], output_core_dims=[[time_dim]],
                                   vectorize=True, kwargs={"h": h}, output_dtypes=[d.dtype])
-            coll.append(filt)
+            # trim data to valid range
+            ext_len = int((len(h) + 1) / 2)
+            valid_range = filt.coords[time_dim].values[ext_len:-ext_len]
+            trimmed = filt.sel(**{time_dim: valid_range})
+            coll.append(trimmed)
         filtered = xr.concat(coll, var_dim)
 
         # create result array with same shape like input data, gaps are filled by nans