Treat NaNs when aggregating scans

src/daxs/measurements.py

@@ -475,19 +475,25 @@ class Measurement1D(Measurement):
             self._monitor = np.zeros_like(self.x)
 
         for scan in self.scans:
-            if mode == "sum":
-                self._signal += scan.signal
-            elif mode == "sum of fractions":
-                self._signal += scan.signal / scan.monitor
-            elif mode == "fraction of sums":
-                self._signal += scan.signal
+            if mode in ("sum", "fraction of sums"):
+                self._signal += np.nan_to_num(scan.signal, nan=0)
+            elif mode in ("sum of fractions",):
+                self._signal += np.nan_to_num(scan.signal, nan=0) / np.nan_to_num(
+                    scan.monitor, nan=1
+                )
             else:
                 raise ValueError(f"Unknown aggregation mode {mode}.")
+
+            # Aggregate monitor when mode is not "sum".
             if mode != "sum" and self._monitor.size > 0:
-                self._monitor += scan.monitor
+                self._monitor += np.nan_to_num(scan.monitor, nan=0)
 
+        # Divide signal by monitor where monitor is not zero. If monitor is zero, the
+        # signal is set to NaN.
         if mode == "fraction of sums":
-            self._signal = self._signal / self._monitor
+            self._signal = np.where(
+                self._monitor != 0, self._signal / self._monitor, np.nan
+            )
 
         logger.info("The scans data was aggregated using the %s mode.", mode)