Code Editor for app.py

import streamlit as st
import pandas as pd
import plotly.express as px
import numpy as np

# Cache the data loading
@st.cache_data
def load_data(url):
    return pd.read_csv(url)

# Title
st.title("Data Visualization App")

# URL input
url = st.text_input(
    "Enter CSV URL",
    value="https://raw.githubusercontent.com/mwaskom/seaborn-data/master/penguins.csv"
)

try:
    # Load the data
    df = load_data(url)
    
    # Shuffle control
    shuffle = st.checkbox("Randomly shuffle data")
    if shuffle:
        df = df.sample(frac=1).reset_index(drop=True)
    
    # Number of rows to display
    n_rows = st.slider("Number of rows to display", 1, len(df), min(10, len(df)))
    
    # Display the dataframe
    st.subheader("Data Preview")
    st.dataframe(df.head(n_rows))
    
    # Variable selection
    columns = df.select_dtypes(include=[np.number, object]).columns
    var1 = st.selectbox("Select first variable", columns)
    var2 = st.selectbox("Select second variable (optional)", ["None"] + list(columns))
    
    if var2 == "None":
        # Single variable visualization
        if df[var1].dtype in [np.number]:
            # Numerical variable - show histogram
            fig = px.histogram(df, x=var1, title=f"Distribution of {var1}")
            st.plotly_chart(fig)
        else:
            # Categorical variable - show bar chart
            fig = px.bar(df[var1].value_counts().reset_index(), 
                        x="index", y=var1,
                        title=f"Distribution of {var1}")
            st.plotly_chart(fig)
    else:
        # Two variable visualization
        if df[var1].dtype in [np.number] and df[var2].dtype in [np.number]:
            # Both numerical - scatter plot
            fig = px.scatter(df, x=var1, y=var2, 
                           title=f"Scatter plot: {var1} vs {var2}")
            st.plotly_chart(fig)
        elif df[var1].dtype in [np.number] and df[var2].dtype not in [np.number]:
            # Numerical and categorical - box plot
            fig = px.box(df, x=var2, y=var1,
                        title=f"Box plot: {var1} by {var2}")
            st.plotly_chart(fig)
        elif df[var1].dtype not in [np.number] and df[var2].dtype in [np.number]:
            # Categorical and numerical - box plot
            fig = px.box(df, x=var1, y=var2,
                        title=f"Box plot: {var2} by {var1}")
            st.plotly_chart(fig)
        else:
            # Both categorical - heatmap
            contingency = pd.crosstab(df[var1], df[var2])
            fig = px.imshow(contingency,
                          title=f"Relationship between {var1} and {var2}")
            st.plotly_chart(fig)

except Exception as e:
    st.error(f"Error: {str(e)}")