Add a Run button to PALS Viewer

[joewandy]

Add a Run button instead of running pathway analysis automatically in PALS Viewer.

A bit messy to do because of: https://discuss.streamlit.io/t/programmable-state-for-streamlit/2052

Right now, getting a Streamlit app to store internal state, like information a user entered in a form, is simply too tricky. There are some workarounds 23 for session state 11, but we want to give you a baked-in and elegant version of programmable state so you can build apps with sequential logic, apps with multiple pages, apps that incrementally ask users for input, and so on. Please share thoughts here 21 about the use cases you’d like to see supported.

There are hacky ways to do it, or maybe it's best to wait until they fix it properly.

• https://gist.github.com/tvst/036da038ab3e999a64497f42de966a92
• https://gist.github.com/tvst/0899a5cdc9f0467f7622750896e6bd7f

[joewandy]

See https://discuss.streamlit.io/t/have-a-widget-not-trigger-an-immediate-update/354

[joewandy]

Implemented the workaround based on the link above.

[joewandy]

The workaround above seems buggy. Reopening this issue to fix it properly.

[joewandy]

Would be good if we also add a Load Example Data button for reviewers.

[joewandy]

Seems like there's a bug if we try to run multiple analyses several times. The metadata from the previous one is still kept around, and users haven't had a chance to change it yet. This won't happen if we have a Run button.