PATCh

This is a directory of web applications built with Python. The apps run entirely in the browser. It uses mainly two libraries:

• streamlit - web applications using simple python code. Check the documentation to learn how to write apps.
• stlite - allows to use stramlit in the browser (using pyodide). If you're just writing apps, you don't have to worry about this.

All you need to do is to write your own streamlit apps and they will be accessible from the directory of apps.

How to start

Here are some quick video guides on how to contribute via GitHub and how to write a basic app if you prefer that to reading.

If not, let's go ahead and create, run and publish a small testing app.

If you just want to see the final result, check this python file which creates this live app.

Setup the editor

1. Start by creating a new branch. This is where your code will live until you are ready to publish your app.

2. Within that branch, go back to the repository main page (where you can read this document) and open the web-based editor on this repository by pressing the . key on the keyboard.

3. Ensure you have the suggested extensions installed - a popup should open on the lower right side of your screen a few seconds after you open this editor. If it doesn't, go to the sidebar of the editor, click on the extensions icon and check the recommended section. You should see a social finance extension called sf-nova (if not, search for it). Install it.

⚠️ please ensure you have installed the sf-nova extension and not the original stlite extension - the latter currently doesn't work while the former is an adaptation written by Social Finance that works properly.

Create an app

1. Go to the apps directory and make a new directory for your app (for example, apps/my_very_first_app) and create your main app python file within it (it can be apps/my_very_first_app/app.py or apps/my_very_first_app/my_very_first_app.py or whatever you want).

2. Let's create a sample app that asks for a username and says hello back to the user. In the file apps/my_very_first_app/app.py add the following code and save it:

   import streamlit as st
   
   name = st.text_input("What's your name?")
   
   if name:
       st.write(f'Hello {name}!')

   In here we:

   • Import the streamlit package
   • ask for the users name with a text input
   • say hello to the user once they submit their name

Preview the app

1. With your app's python file opened (and focused), click on the sf-nova icon on the sidebar (it should be the one bellow the github icon) and press "Launch preview".

   

2. You can also run it from vscode command palette: ctrl + shift + P and search for the command launch streamlit preview. You should now see a preview on the right side of your editor, while your app's code is in your left side:

   

3. You can now edit the code and, once you save the python file, it will update the app's preview accordingly. If it doesn't, edit the settings of your streamlit preview screen (on the top right button) and check the "Run on save" option - that will ensure your preview reloads every time you change something in your code (and save the file(s)).

4. If you need to use external libraries (such as matplotlib to render charts or openpyxl to read excel files) ensure that those libraries are listed in a requirements.txt file in the same directory as your python file is. Check this example for guidance.

5. Once you are happy with your changes, you are ready to publish your app (pending on approval) by making a pull request with your new app. Once your code is approved and merged, it will be displayed in the directory of apps in https://patch.datatoinsight.org.