Streamlit app showing the result as NONE but in the terminal appears

Question

I created an app using Streamlit. I am trying to display the result but it is displayed only in the terminal and the interface shows NONE. there are no errors shown, all works perfect. Here is my code:

import pickle
import numpy as np 
import streamlit as st

loaded_model=pickle.load(open("C:/trained_model.sav",'rb'))

def prediction(input_data):
    input_data_numpy= np.asarray(input_data)
    input_data_reshape=input_data_numpy.reshape(1,-1)
    prediction=loaded_model.predict(input_data_reshape)
    print(prediction)
    
def main():
    st.title("Predict quantity")
    strain = st.radio("strain:",("cereal","sugar","salt"))
    plNr=st.slider('Number of plants:', 10, 2340, 25)
    result = ""
    if strain == "cereal":
        strain = 1
    elif strain == "sugar":
        strain = 2
    else:
        strain = 3
    if st.button("result"):
        result= prediction([strain,plNr])
    st.success(result)

if __name__ =="__main__":
    main()

(py108) C:\Users\s>streamlit run "C:\Users\prediction.py" You can now view your Streamlit app in your browser.

Local URL: http://localhost:8501 Network URL:

[[0.42784861]]

My terminal shows the result: [[0.42784861]] but the interface shows like this: Can anyone help me out please?

Answer 1

You didn't return anything from the prediction function, hence the None value.

I'd highly recommend you to use type hints, so that these errors are caught by the IDE.