Output a message when no title or abstract provided

app.py

@@ -50,7 +50,7 @@ def predict_and_decode(model, title='', abstract=''):
     return df.reset_index(drop=True)
 
 st.header("Paper Category Classifier")
-st.text("Input title and/or abstract of a scientific paper, and get classification according to arxiv.org categories")
+st.text("Input a title and/or an abstract of a scientific paper, and get classification according to arxiv.org categories")
 
 title_default = "Attention Is All You Need"
 abstract_default = (
@@ -64,19 +64,22 @@ n_lines = 10
 title = st.text_input("Paper title", value=title_default, help="Type in paper's title")
 abstract = st.text_area("Paper abstract", value=abstract_default, height=line_height*n_lines, help="Type in paper's abstract")
 
-result = predict_and_decode(model, title=title, abstract=abstract)
-
-cnt = st.container(border=True)
-with cnt:
-    st.markdown("#### Top category")
-    st.markdown(f"**{result.tag[0]}** -- {result.name[0]}")
-    st.markdown(f"Probability: {result.probability[0]*100:.2f}%")
-
-threshold = 0.55
-st.text("Other top categories:")
-max_len = min(max(1, sum(result.iloc[1:].probability > threshold)), 5)
-
-def format_p(example):
-    example.probability = f"{example.probability * 100 :.2f}%"
-    return example
-st.table(result.iloc[1:1 + max_len].apply(format_p, axis=1))
+if title or abstract:
+    result = predict_and_decode(model, title=title, abstract=abstract)
+
+    cnt = st.container(border=True)
+    with cnt:
+        st.markdown("#### Top category")
+        st.markdown(f"**{result.tag[0]}** -- {result.name[0]}")
+        st.markdown(f"Probability: {result.probability[0]*100:.2f}%")
+
+    threshold = 0.55
+    st.text("Other top categories:")
+    max_len = min(max(1, sum(result.iloc[1:].probability > threshold)), 5)
+
+    def format_p(example):
+        example.probability = f"{example.probability * 100 :.2f}%"
+        return example
+    st.table(result.iloc[1:1 + max_len].apply(format_p, axis=1))
+else:
+    st.warning("Type a title and/or an abstract to get started!")