Update app.py

app.py

@@ -34,7 +34,7 @@ def prediction(file):
 
 # file uploader
 
-uploaded_file = st.file_uploader("Choose a leaf picture:")
+uploaded_file = st.file_uploader("Upload your leaf picture.")
 if uploaded_file is not None:
     image = Image.open(uploaded_file)
     image = image.resize((240, 240))
@@ -44,6 +44,9 @@ if uploaded_file is not None:
   
 # result
 
-if st.button('Predict'): 
-    result = prediction(uploaded_file)
-    st.write('This leaf belongs to {} class'.format(result))
+if st.button('Predict'):
+    if uploaded_file is None:
+        st.write('Please upload a leaf picture first.')
+    else:
+        result = prediction(uploaded_file)
+        st.write('This leaf belongs to {} class.'.format(result))