Fixes

app.py

@@ -60,14 +60,20 @@ with st.form("files"):
     # Ask for relations file.
     csv_edges = st.file_uploader(label="Upload file with **relations**.", key="relations", help=f'[Example]({info.relations_example})')
 
-    sep = st.radio('Separator in your files:', options=[',', ';', 'tab'])
-    if sep == 'tab':
-        sep='\t'
-    
-    files_uploaded = st.form_submit_button("Ok")
+    sep = st.radio('Separator in your files:', options=['comma ( , )', 'semicolon ( ; )', 'tab ( \u21E5 )'], help='What are the values in your files separated with?')
+
+    files_uploaded = st.form_submit_button("Done")
 
 if files_uploaded:
-    df = pd.read_csv(csv_edges, sep=sep)
+    separators = {'comma ( , )': ',', 'semicolon ( ; )': ';', 'tab ( \u21E5 )': '\t'}
+    if 'sep' not in st.session_state:
+        st.session_state["sep"] =  separators[sep]
+
+    if csv_edges == None:
+        st.markdown(':red[You need to upload a file with relations.]')
+        st.stop()
+
+    df = pd.read_csv(csv_edges, sep=st.session_state["sep"])
 
     df.rename({'type': 'relation_type'}, inplace=True, axis=1) # 'type' can't be used as attribute.
     df.columns = [i.lower() for i in df.columns] # Remove capital letters from column names.
@@ -113,7 +119,7 @@ if files_uploaded:
         )
 
         if csv_nodes != None: # When a nodes file is uploaded.
-            df_nodes = pd.read_csv(csv_nodes, sep=sep)
+            df_nodes = pd.read_csv(csv_nodes, sep=st.session_state["sep"])
             df_nodes.columns = [i.lower() for i in df_nodes.columns] # Remove capital letters from column names.
             columns = df_nodes.columns.tolist()
             if "label" in columns:
@@ -136,7 +142,7 @@ if files_uploaded:
             df_nodes.set_index("labels", inplace=True)
 
         gexf_file = "output.gexf"
-        #with open(gexf_file) as f:
+
         # Make empty graph.
         G = nx.MultiDiGraph()
         # Add nodes.
@@ -146,7 +152,7 @@ if files_uploaded:
             G, df, source=source, target=target, chosen_columns=chosen_columns
         )
 
-        # Turn the graph into text.
+        # Turn the graph into a string.
         graph_text = "\n".join([line for line in nx.generate_gexf(G)])
         
         # Download gexf-file.