Live Display¶

Progress bars and status indicators use a live display to animate parts of the terminal. You can build custom live displays with the Live class.

For a demonstration of a live display, run the following command:

python -m rich.live

Note

If you see ellipsis “…”, this indicates that the terminal is not tall enough to show the full table.

Basic usage¶

To create a live display, construct a Live object with a renderable and use it as a context manager. The live display will persist for the duration of the context. You can update the renderable to update the display:

import time

from rich.live import Live
from rich.table import Table

table = Table()
table.add_column("Row ID")
table.add_column("Description")
table.add_column("Level")

with Live(table, refresh_per_second=4):  # update 4 times a second to feel fluid
    for row in range(12):
        time.sleep(0.4)  # arbitrary delay
        # update the renderable internally
        table.add_row(f"{row}", f"description {row}", "[red]ERROR")

Updating the renderable¶

You can also change the renderable on-the-fly by calling the update() method. This may be useful if the information you wish to display is too dynamic to generate by updating a single renderable. Here is an example:

import random
import time

from rich.live import Live
from rich.table import Table


def generate_table() -> Table:
    """Make a new table."""
    table = Table()
    table.add_column("ID")
    table.add_column("Value")
    table.add_column("Status")

    for row in range(random.randint(2, 6)):
        value = random.random() * 100
        table.add_row(
            f"{row}", f"{value:3.2f}", "[red]ERROR" if value < 50 else "[green]SUCCESS"
        )
    return table


with Live(generate_table(), refresh_per_second=4) as live:
    for _ in range(40):
        time.sleep(0.4)
        live.update(generate_table())

Alternate screen¶

You can opt to show a Live display in the “alternate screen” by setting screen=True on the constructor. This will allow your live display to go full screen and restore the command prompt on exit.

You can use this feature in combination with Layout to display sophisticated terminal “applications”.

Transient display¶

Normally when you exit live context manager (or call stop()) the last refreshed item remains in the terminal with the cursor on the following line. You can also make the live display disappear on exit by setting transient=True on the Live constructor.

Auto refresh¶

By default, the live display will refresh 4 times a second. You can set the refresh rate with the refresh_per_second argument on the Live constructor. You should set this to something lower than 4 if you know your updates will not be that frequent or higher for a smoother feeling.

You might want to disable auto-refresh entirely if your updates are not very frequent, which you can do by setting auto_refresh=False on the constructor. If you disable auto-refresh you will need to call refresh() manually or update() with refresh=True.

Vertical overflow¶

By default, the live display will display ellipsis if the renderable is too large for the terminal. You can adjust this by setting the vertical_overflow argument on the Live constructor.

“crop” Show renderable up to the terminal height. The rest is hidden.
“ellipsis” Similar to crop except last line of the terminal is replaced with “…”. This is the default behavior.
“visible” Will allow the whole renderable to be shown. Note that the display cannot be properly cleared in this mode.

Note

Once the live display stops on a non-transient renderable, the last frame will render as visible since it doesn’t have to be cleared.

Print / log¶

The Live class will create an internal Console object which you can access via live.console. If you print or log to this console, the output will be displayed above the live display. Here’s an example:

import time

from rich.live import Live
from rich.table import Table

table = Table()
table.add_column("Row ID")
table.add_column("Description")
table.add_column("Level")

with Live(table, refresh_per_second=4) as live:  # update 4 times a second to feel fluid
    for row in range(12):
        live.console.print(f"Working on row #{row}")
        time.sleep(0.4)
        table.add_row(f"{row}", f"description {row}", "[red]ERROR")

If you have another Console object you want to use, pass it in to the Live constructor. Here’s an example:

from my_project import my_console

with Live(console=my_console) as live:
    my_console.print("[bold blue]Starting work!")
    ...

Note

If you are passing in a file console, the live display only show the last item once the live context is left.

Redirecting stdout / stderr¶

To avoid breaking the live display visuals, Rich will redirect stdout and stderr so that you can use the builtin print statement. This feature is enabled by default, but you can disable by setting redirect_stdout or redirect_stderr to False.

Nesting Lives¶

Note that only a single live context may be active at any one time. The following will raise a LiveError because status also uses Live:

with Live(table, console=console):
    with console.status("working"):  # Will not work
        do_work()

In practice this is rarely a problem because you can display any combination of renderables in a Live context.

Examples¶

See table_movie.py and top_lite_simulator.py for deeper examples of live displaying.