Index: trunk/SDToolBox/data_processing.py
===================================================================
diff -u -r67 -r68
--- trunk/SDToolBox/data_processing.py	(.../data_processing.py)	(revision 67)
+++ trunk/SDToolBox/data_processing.py	(.../data_processing.py)	(revision 68)
@@ -130,7 +130,8 @@
             frequency_string=frequency_string
         )
 
-    def compute_spatial_gradients(self, data_array: xr.DataArray):
+    @staticmethod
+    def compute_spatial_gradients(data_array: xr.DataArray):
 
         meshed_latitudes, meshed_longitudes = \
             np.meshgrid(
@@ -206,7 +207,8 @@
         return data_array
         # probably here we need to use .assign_coords function to add grad2slp to the existing array
 
-    def compute_PCA(self, data_array: xr.DataArray):
+    @staticmethod
+    def compute_PCA(data_array: xr.DataArray):
 
         grad2slp = data_array.attrs['grad2slp']
 
@@ -215,7 +217,7 @@
 
         scaler = StandardScaler(with_mean=True, with_std=True)
         scaler.fit(grad2slp)
-        transformed_grad2slp = scaler.transform(grad2slp) #normalizing the features
+        transformed_grad2slp = scaler.transform(grad2slp) # normalizing the features
         exvar = 99.88/100
         pca = skPCA(n_components=exvar)
         pca.fit(transformed_grad2slp)