streamlit notes

1

Basic Text Display: Can you display a simple text message in your Streamlit app?

import streamlit as st

# Displaying text
st.write("Hello, Streamlit!")

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2

User Input: How can users input their name into your Streamlit app?

import streamlit as st

# Text input widget
name = st.text_input("Enter your name", "")
st.write("Hello,", name)

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3

Interactive Widgets: Can you create a slider to adjust a numeric value in your app?

import streamlit as st

# Slider widget
value = st.slider("Select a value", 0, 100, 50)
st.write("Selected value:", value)

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4

Data Visualization: How can you display a simple plot in your Streamlit app?

import streamlit as st
import matplotlib.pyplot as plt
import numpy as np

# Generate data
x = np.linspace(0, 10, 100)
y = np.sin(x)

# Plotting
fig, ax = plt.subplots()
ax.plot(x, y)
st.pyplot(fig)

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5

File Upload: How can users upload a CSV file into your Streamlit app?

import streamlit as st
import pandas as pd

# File uploader
uploaded_file = st.file_uploader("Upload a CSV file", type=["csv"])

# Display file contents
if uploaded_file is not None:
    data = pd.read_csv(uploaded_file)
    st.write(data)

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6

Data Filtering: How can users filter a DataFrame based on a specific column value?

import streamlit as st
import pandas as pd

# Load data
data = pd.read_csv("data.csv")

# Selectbox for filtering
selected_category = st.selectbox("Select category", data["Category"].unique())

# Filter data
filtered_data = data[data["Category"] == selected_category]

# Display filtered data
st.write(filtered_data)

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7

Interactive Buttons: Can you create a button that triggers an action when clicked?

import streamlit as st

# Button widget
if st.button("Click me"):
    st.write("Button clicked!")

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8

Multiple Pages: How can you create multiple pages in your Streamlit app using st.sidebar?

import streamlit as st

# Sidebar navigation
page = st.sidebar.selectbox("Select a page", ["Home", "About", "Contact"])

# Display different content based on page selection
if page == "Home":
    st.write("Welcome to the Home page.")
elif page == "About":
    st.write("This is the About page.")
else:
    st.write("Contact us at [e-mail]")

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9

Custom Plots: How can you create a custom plot using Plotly in your Streamlit app?

import streamlit as st
import plotly.graph_objects as go

# Create a Plotly figure
fig = go.Figure(data=go.Bar(x=[1, 2, 3], y=[4, 1, 2]))

# Display the plot
st.plotly_chart(fig)

10

Real-time Updates: How can you update content in your Streamlit app in real-time?

import streamlit as st
import time

# Displaying a progress bar
progress_bar = st.progress(0)
for i in range(100):
    time.sleep(0.1)
    progress_bar.progress(i + 1)

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11

Custom CSS: Can you apply custom CSS styles to elements in your Streamlit app?

import streamlit as st

# Applying custom CSS
st.markdown("""
    <style>
        .custom-text {
            color: red;
            font-size: 24px;
        }
    </style>
""", unsafe_allow_html=True)

# Displaying text with custom style
st.write('<div class="custom-text">Custom text</div>', unsafe_allow_html=True)

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12

Error Handling: How can you handle errors gracefully in your Streamlit app?

import streamlit as st

# Error handling
try:
    # Code that may raise an error
    result = 1 / 0
    st.write("Result:", result)
except Exception as e:
    st.error(f"An error occurred: {e}")

---

13

Data Download: How can users download data generated in your Streamlit app?

import streamlit as st
import pandas as pd

# Downloadable data link
download_link = st.sidebar.button("Download Data")

# Generate and display data
data = pd.DataFrame({"A": [1, 2, 3], "B": [4, 5, 6]})
st.write(data)

# Create a download link
if download_link:
    csv = data.to_csv(index=False)
    st.download_button(label="Download CSV", data=csv, file_name="data.csv", mime="text/csv")

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14

Markdown and HTML: How can you include Markdown and HTML content in your Streamlit app?

import streamlit as st

# Markdown and HTML content
st.markdown("## Markdown Heading")
st.write('<div style="color: blue;">HTML content</div>', unsafe_allow_html=True)

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15

Deploying External Services: How can you deploy your Streamlit app to an external service like Heroku?

# Example of Streamlit app code (app.py)

import streamlit as st

def main():
    st.title("My Streamlit App")
    st.write("Hello, Streamlit!")

if __name__ == "__main__":
    main()