export one first write

festim/exports/surface_flux.py

@@ -41,11 +41,3 @@ def compute(self, n, ds):
             )
         )
         self.data.append(self.value)
-
-    def initialise_export(self):
-        title = "Flux surface {}: {}".format(self.surface.id, self.field.name)
-
-        if self.filename is not None:
-            with open(self.filename, mode="w", newline="") as file:
-                writer = csv.writer(file)
-                writer.writerow(["t(s)", f"{title}"])

festim/exports/surface_quantity.py

@@ -1,5 +1,6 @@
 import festim as F
 import csv
+import os
 
 
 class SurfaceQuantity:
@@ -63,6 +64,14 @@ def field(self, value):
         self._field = value
 
     def write(self, t):
+        if not os.path.isfile(self.filename):
+            title = "Flux surface {}: {}".format(self.surface.id, self.field.name)
+
+            if self.filename is not None:
+                with open(self.filename, mode="w", newline="") as file:
+                    writer = csv.writer(file)
+                    writer.writerow(["t(s)", f"{title}"])
+
         with open(self.filename, mode="a", newline="") as file:
             writer = csv.writer(file)
             writer.writerow([t, self.value])

festim/hydrogen_transport_problem.py

@@ -250,8 +250,6 @@ def initialise_exports(self):
                 export.define_writer(MPI.COMM_WORLD)
                 if isinstance(export, F.XDMFExport):
                     export.writer.write_mesh(self.mesh.mesh)
-            elif isinstance(export, F.SurfaceQuantity):
-                export.initialise_export()
 
         # compute diffusivity function for surface fluxes