diff --git a/Analysis/mat_to_shapefiles.py b/Analysis/mat_to_shapefiles.py
index 169c497c73680d672aaf1fc6003883e548e4f447..17d0debff7030a1047816bcc7c496ba765621654 100755
--- a/Analysis/mat_to_shapefiles.py
+++ b/Analysis/mat_to_shapefiles.py
@@ -80,6 +80,9 @@ def write(writers, cell, cyclone):
         polyline = np.stack((eddy[8], eddy[9]), axis = 1)
         writers["max_speed"].poly([polyline])
 
+    n_shapes = len(writers["extr"])
+    writers["ishape_last"].write(str(n_shapes - 1) + "\n")
+
 year = 2019
 my_date = datetime.date(year, 12, 15)
 final_date = datetime.date(year, 12, 15)
@@ -101,6 +104,8 @@ for f in factories:
                                                  shapeType = shapefile.POLYGON)
     
     define_fields(f["writers"])
+    file = path.join(f["SHP_triplet"], "ishape_last.txt")
+    f["writers"]["ishape_last"] = open(file, "w")
     
 while my_date <= final_date:
     adt_file = my_date.strftime("adt_%Y-%m-%d_v6.mat")