dataPreprocessor.py

import pandas as pd
import streamlit as st

@st.cache_data
def preprocess(file):
    # parse text and create list of lists structure
    processed_data = []
    for line in file:
        # grab the info and cut it out
        line = str(line.decode('utf-8'))
        date = line.split(",")[0]
        line = line[len(date):]
        time = line.split("-")[0][2:]
        line = line[2 + len(time):]
        user = line.split(":")[0][2:]
        line = line[2 + len(user):]
        message = line[2:-1] # strip newline character
        processed_data.append([date, time, user, message])

    # Create the DataFrame 
    df = pd.DataFrame(processed_data, columns = ['Date', 'Time', 'User', 'Message']) 

    df['datetime'] = pd.to_datetime(df['Date'] + ' ' + df['Time'],errors='coerce')
    df = df.dropna(subset=['datetime'])
    df['year'] = df['datetime'].dt.year
    df['month_name'] = df['datetime'].dt.month_name()
    df['day_name'] = df['datetime'].dt.day_name()
    df['hour'] = df['datetime'].dt.hour

    # filter the DataFrame to remove whatsapp info message
    df = df[df.Message != '']
    
    return df