One of the strong points of panel is that is reactive. As we described in the vega tutorial, in a reactive program any change in a variable will automatically be reflected in other variables that depend on it.

Let’s create a small panel with a title and a bit of text:

title = pn.pane.Markdown("# This is my title")
text = pn.pane.Markdown("This is the text")
pn.Column(title, text)

As expected, this is what we get:

This is my title

This is the text

The title variable is much more than just a bit of text. You can see that is you check what methods are available on it: write title. (with the period) and try tab-completion. Calling title.object will give you the text contained in the variable: # This is my title. We can use that to change the text:

title.object = "# This is my new title"

Now automatically, the previous output will be changed into

This is my new title

This is the text

So you don’t have to re-run cells in the notebook to update their output, and any data streams will be dynamically reflected.