Create app.py

app.py

@@ -0,0 +1,221 @@
+import streamlit as st
+
+def main():
+    st.set_page_config(
+        page_title="Learn Streamlit",
+        page_icon="📚",
+        layout="wide",
+        initial_sidebar_state="expanded"
+    )
+    
+    st.title("📚 Streamlit Learning App")
+    st.markdown("Learn Streamlit by exploring this interactive app!")
+    
+    # Sidebar navigation
+    st.sidebar.title("Navigation")
+    page = st.sidebar.radio(
+        "Go to",
+        ["Home", "Basic Elements", "Layouts", "Widgets", "Advanced Features"]
+    )
+    
+    if page == "Home":
+        show_home()
+    elif page == "Basic Elements":
+        show_basic_elements()
+    elif page == "Layouts":
+        show_layouts()
+    elif page == "Widgets":
+        show_widgets()
+    elif page == "Advanced Features":
+        show_advanced_features()
+
+def show_home():
+    st.header("Welcome to Streamlit Learning!")
+    st.markdown("""
+    This app demonstrates various Streamlit features while teaching you how to use them.
+    
+    **How to use this app:**
+    1. Select a topic from the sidebar
+    2. See live examples of Streamlit code
+    3. View the code that creates each example
+    4. Try modifying the code in the expanders
+    """)
+    
+    st.image("https://streamlit.io/images/brand/streamlit-logo-secondary-colormark-darktext.png", width=300)
+    
+    with st.expander("Quick Streamlit Facts"):
+        st.markdown("""
+        - Streamlit turns data scripts into shareable web apps in minutes
+        - No front-end experience required
+        - Pure Python
+        - Open source (Apache License 2.0)
+        - First released in October 2019
+        """)
+
+def show_basic_elements():
+    st.header("Basic Streamlit Elements")
+    
+    st.subheader("Text Elements")
+    st.code("""
+    st.title("This is a title")  # Displays text in title formatting
+    st.header("This is a header")  # Section header
+    st.subheader("This is a subheader")  # Subsection header
+    st.text("This is plain text")  # Fixed-width and monospace text
+    st.markdown("This is **markdown**")  # Markdown formatting
+    st.write("This is multi-purpose write")  # Can handle multiple arguments
+    """)
+    
+    st.subheader("Display Elements")
+    st.code("""
+    st.dataframe(pandas_dataframe)  # Interactive dataframe
+    st.table(static_data)  # Static table
+    st.json({"key": "value"})  # Interactive JSON
+    st.metric("Metric", 42, delta=1.2)  # Metric display
+    """)
+    
+    col1, col2 = st.columns(2)
+    with col1:
+        st.info("This is an info message")
+        st.success("This is a success message!")
+    with col2:
+        st.warning("This is a warning message")
+        st.error("This is an error message")
+
+def show_layouts():
+    st.header("Streamlit Layouts")
+    
+    st.subheader("Columns")
+    st.code("""
+    col1, col2 = st.columns(2)  # Create two columns
+    with col1:
+        st.write("Content in column 1")
+    with col2:
+        st.write("Content in column 2")
+    """)
+    
+    # Example of columns
+    col1, col2, col3 = st.columns([1, 2, 1])
+    with col1:
+        st.write("Narrow column")
+    with col2:
+        st.write("Wide column")
+    with col3:
+        st.write("Another narrow column")
+    
+    st.subheader("Expander")
+    st.code("""
+    with st.expander("Click to expand"):
+        st.write("Hidden content that appears when expanded")
+    """)
+    
+    with st.expander("Example Expander"):
+        st.write("This content was hidden but now it's visible!")
+        st.image("https://via.placeholder.com/150", width=100)
+    
+    st.subheader("Tabs")
+    st.code("""
+    tab1, tab2 = st.tabs(["Tab 1", "Tab 2"])
+    with tab1:
+        st.write("Content for tab 1")
+    with tab2:
+        st.write("Content for tab 2")
+    """)
+    
+    tab1, tab2 = st.tabs(["First Tab", "Second Tab"])
+    with tab1:
+        st.write("This is the first tab")
+    with tab2:
+        st.write("This is the second tab")
+
+def show_widgets():
+    st.header("Streamlit Widgets")
+    
+    st.subheader("Input Widgets")
+    st.code("""
+    st.button("Click me")  # Button
+    st.checkbox("I agree")  # Checkbox
+    st.radio("Choose one", ["A", "B", "C"])  # Radio buttons
+    st.selectbox("Select", ["Option 1", "Option 2"])  # Dropdown select
+    st.multiselect("Choose many", ["A", "B", "C"])  # Multi-select
+    st.slider("Slide", 0, 100)  # Slider
+    st.select_slider("Slide to select", ["Bad", "Good", "Excellent"])  # Select slider
+    st.text_input("Enter text")  # Text input
+    st.number_input("Enter number")  # Number input
+    st.text_area("Enter long text")  # Text area
+    st.date_input("Pick a date")  # Date input
+    st.time_input("Pick a time")  # Time input
+    st.file_uploader("Upload a file")  # File uploader
+    st.color_picker("Pick a color")  # Color picker
+    """)
+    
+    # Interactive widget demo
+    col1, col2 = st.columns(2)
+    with col1:
+        name = st.text_input("What's your name?")
+        age = st.slider("How old are you?", 0, 100, 25)
+        color = st.color_picker("Pick your favorite color")
+    with col2:
+        if name:
+            st.write(f"Hello, {name}!")
+        st.write(f"You're {age} years old")
+        st.write("Your favorite color is:")
+        st.markdown(f'<div style="width:100%; height:50px; background:{color};"></div>', unsafe_allow_html=True)
+
+def show_advanced_features():
+    st.header("Advanced Streamlit Features")
+    
+    st.subheader("Session State")
+    st.code("""
+    # Initialize session state
+    if 'counter' not in st.session_state:
+        st.session_state.counter = 0
+    
+    # Increment counter
+    if st.button('Increment'):
+        st.session_state.counter += 1
+    
+    st.write('Count:', st.session_state.counter)
+    """)
+    
+    # Session state example
+    if 'counter' not in st.session_state:
+        st.session_state.counter = 0
+    
+    col1, col2, col3 = st.columns(3)
+    with col1:
+        if st.button('Increment'):
+            st.session_state.counter += 1
+    with col2:
+        if st.button('Decrement'):
+            st.session_state.counter -= 1
+    with col3:
+        if st.button('Reset'):
+            st.session_state.counter = 0
+    
+    st.write('Current count:', st.session_state.counter)
+    
+    st.subheader("Caching")
+    st.code("""
+    @st.cache_data  # Cache data processing functions
+    def expensive_computation(a, b):
+        time.sleep(2)  # Simulate slow computation
+        return a * b
+    
+    result = expensive_computation(5, 10)
+    st.write(result)
+    """)
+    
+    import time
+    @st.cache_data
+    def expensive_computation(a, b):
+        time.sleep(2)  # Simulate slow computation
+        return a * b
+    
+    if st.button("Run expensive computation (cached)"):
+        result = expensive_computation(5, 10)
+        st.write("Result:", result)
+    
+    st.info("Notice how the cached version runs instantly after the first run!")
+
+if __name__ == "__main__":
+    main()