app.py

import streamlit as st
import math

# Define the conversion table from French to Ewbank grades
french_to_ewbank = {
    '4a/4a+': 13, '4b/4b+': 14, '4c/4c+': 15,
    '5a': 15.5, '5a+/5b': 16, '5b+': 17, '5c': 17.5, 
    '5c+/6a': 18, '6a+': 19,
    '6b': 20, '6b+': 21, '6c': 21.5, '6c+': 22.5, 
    '7a': 23, '7a+': 24, '7b': 25, '7b+': 26,
    '7c': 27, '7c+': 28, '8a': 29, '8a+': 30,
    '8b': 31, '8b+': 32, '8c': 33, '9a': 35,
    '9b': 37, '9c': 39
}

# Function to convert French grades to Ewbank grades
def convert_french_to_ewbank(french_grade):
    return french_to_ewbank.get(french_grade, None)

# Function to calculate the probability of success
def calculate_probability_of_success(current_grade_ewbank, route_grade_ewbank, m_parameter):
    probability_success = 1 / (math.exp(m_parameter * (route_grade_ewbank - current_grade_ewbank)) + 1)
    expected_attempts = (1 - probability_success) / probability_success
    return probability_success, expected_attempts

# Streamlit app
def main():
    st.title("Climbing Grade Success Estimator")

    # Sidebar for references
    st.sidebar.header("How it works?")
    st.sidebar.write("""Based on the work presented in the paper 'Bayesian inference of the climbing grade scale' available on [ArXiv](https://arxiv.org/abs/2111.08140)""")
    
    st.sidebar.write("""\n\n[Here you can find a table for grade conversion](https://www.thecrag.com/en/article/grades)""")
    
    st.sidebar.header("\n\nOriginal Paper Citation:")
    st.sidebar.text("""
@misc{drummond2021bayesian,
    title={Bayesian inference of the climbing grade scale}, 
    author={Alexei Drummond and Alex Popinga},
    year={2021},
    eprint={2111.08140},
    archivePrefix={arXiv},
    primaryClass={stat.AP}
}
""")

    st.sidebar.write("""\n\nDeveloped by Edoardo Bianchi""")

    st.write("Select your current climbing grade and the grade of the route you plan to climb. Grades are expressed following the French system.")
    current_grade_french = st.selectbox("Climber's Current Grade (French)", options=list(french_to_ewbank.keys()))
    route_grade_french = st.selectbox("Route Grade (French)", options=list(french_to_ewbank.keys()))
    m_parameter = 0.85  # Slope parameter from the paper for Ewbank scale

    if st.button("Estimate Probability"):
        current_grade_ewbank = convert_french_to_ewbank(current_grade_french)
        route_grade_ewbank = convert_french_to_ewbank(route_grade_french)
        probability, attempts = calculate_probability_of_success(current_grade_ewbank, route_grade_ewbank, m_parameter)
        st.success(f"Probability of Success: {probability*100:.2f}%")
        st.success(f"Expected Number of Attempts: {attempts:.2f}")

if __name__ == "__main__":
    main()