Now that you’ve mastered Streamlit’s main concepts, let’s take a look at some advanced functionality, like styling data, adjusting the order of elements in a report, and adding animations.
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Insert elements out of order¶
You can use the
st.empty method as a placeholder,
to “save” a slot in your app that you can use later.
st.text('This will appear first') # Appends some text to the app. my_slot1 = st.empty() # Appends an empty slot to the app. We'll use this later. my_slot2 = st.empty() # Appends another empty slot. st.text('This will appear last') # Appends some more text to the app. my_slot1.text('This will appear second') # Replaces the first empty slot with a text string. my_slot2.line_chart(np.random.randn(20, 2)) # Replaces the second empty slot with a chart.
Let’s combine some of the things you’ve learned to create compelling animations in your app.
progress_bar = st.progress(0) status_text = st.empty() chart = st.line_chart(np.random.randn(10, 2)) for i in range(100): # Update progress bar. progress_bar.progress(i + 1) new_rows = np.random.randn(10, 2) # Update status text. status_text.text( 'The latest random number is: %s' % new_rows[-1, 1]) # Append data to the chart. chart.add_rows(new_rows) # Pretend we're doing some computation that takes time. time.sleep(0.1) status_text.text('Done!') st.balloons()
Append data to a table or chart¶
In Streamlit, you can not only replace entire elements in your app, but also modify the data behind those elements. Here is how:
import numpy as np import time # Get some data. data = np.random.randn(10, 2) # Show the data as a chart. chart = st.line_chart(data) # Wait 1 second, so the change is clearer. time.sleep(1) # Grab some more data. data2 = np.random.randn(10, 2) # Append the new data to the existing chart. chart.add_rows(data2)
Record a screencast¶
After you’ve built a Streamlit app, you may want to discuss some of it with co-workers over email or Slack, or share it with the world on Twitter. A great way to do that is with Streamlit’s built-in screencast recorder. With it, you can record, narrate, stop, save, and share with a few clicks.
To start a screencast, locate the menu in the upper right corner of your app (☰), select Record a screencast, and follow the prompts. Before the recording starts, you’ll see a countdown — this means it’s showtime.
To stop your screencast, go back to the menu (☰) and select Stop recording (or hit the ESC key). Follow the prompts to preview your recording and save it to disk. That’s it, you’re ready to share your Streamlit app.