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textual-plotext

PlotextPlot in action

A Textual widget wrapper for the Plotext plotting library.

Introduction

The library makes one widget available: PlotextPlot. This widget provides a plt property, which should be used where you would normally use plt as seen in the Plotext documentation.

Let's take the first example from the Plotext README:

import plotext as plt
y = plt.sin() # sinusoidal test signal
plt.scatter(y)
plt.title("Scatter Plot") # to apply a title
plt.show() # to finally plot

The Textual equivalent of this (including everything needed to make this a fully-working Textual application) is:

from textual.app import App, ComposeResult

from textual_plotext import PlotextPlot

class ScatterApp(App[None]):

    def compose(self) -> ComposeResult:
        yield PlotextPlot()

    def on_mount(self) -> None:
        plt = self.query_one(PlotextPlot).plt
        y = plt.sin() # sinusoidal test signal
        plt.scatter(y)
        plt.title("Scatter Plot") # to apply a title

if __name__ == "__main__":
    ScatterApp().run()

The main differences to note are:

  • We're not directly importing plotext.
  • We use PlotextPlot.plt rather than plt.
  • We don't call Plotext's show method, PlotextPlot takes care of this.

Installation

The library can be installed from PyPi:

$ pip install textual-plotext

Once installed you can quickly test the library by running the demo:

$ python -m textual_plotext

The demo app includes many of the examples shown in the Plotext README.

Longer example

For a longer example of how to use the PlotextPlot widget, take a look at examples/textual_towers_weather.py. As a bonus it also shows an example of using Textual's worker API to create a threaded worker to pull the data from the backend.

What is supported?

The following utility functions are provided (via PlotextPlot.plt):

  • plt.sin
  • plt.square
  • plt.colorize
  • plt.uncolorize

What isn't supported?

Some functions are not supported at all; mainly those that would not make sense inside a Textual application. These include:

  • plt.interactive
  • plt.script_folder
  • plt.parent_folder
  • plt.join_paths
  • plt.save_text
  • plt.read_data
  • plt.write_data
  • plt.download
  • plt.delete_file
  • plt.test
  • plt.time
  • plt.test_data_url
  • plt.test_bar_data_url
  • plt.test_image_url
  • plt.test_gif_url
  • plt.test_video_url
  • plt.test_youtube_url

The following properties and sub-modules also aren't exposed because they too are designed for REPL-based interactive use and don't lend themselves to being used in a Textual application:

  • plt.doc
  • plt.markers
  • plt.colors
  • plt.styles
  • plt.themes

Also, currently, there is no support for GIF plots or playing videos; one or both could follow at some point in the future.

What functions are no-ops?

Some functions are supported as calls but are redefined to be non-operations; these are the sorts of code that wouldn't generally have a negative side-effect but which don't make sense for a Textual application. These include:

  • plt.clear_terminal
  • plt.show
  • plt.save_fig

Themes

Plotext has a system of themes. The themes provided by Plotext are supported by PlotextPlot. However, some of those themes use "ANSI colors" and so may end up looking different depending on which terminal you use, and what terminal theme is in use (if your terminal supports themes); the issue here is that your plots may look very different in different environments.

To help with this textual-plotext provides an additional set of copies of those themes, all prefixed with textual-, that use full RGB coloring to ensure that, when using a given Plotext theme, it will look the same everywhere.

In addition to the Plotext themes, textual-plotext also adds two themes called:

  • textual-design-dark
  • textual-design-light

These are two similar themes designed to look good in dark mode and light mode respectively. Out of the box, PlotextPlot will use these and will switch between them when your Textual application switches between dark and light mode. If you wish to turn off this behaviour, simply set the auto_theme property of your plot to False.

Known issues

At the moment, due to what appears to be a bug in Plotext when it comes to repeated calls to show or build1 for a plot with x or y scales set to "log", it isn't possible to easily build such a plot. In other words, even in the REPL with Plotext itself, a session such as this:

>>> import plotext as plt
>>> plt.xscale("log")
>>> plt.plot(plt.sin(periods=2, length=10**4))
>>> plt.show()
<plot is drawn in the terminal here>
>>> plt.show()

results in a ValueError: math domain error.

There is a workaround for this, which will work for Plotext use in general and would also work nicely in a Textual app. After the first show or build, set the problematic scale back to "linear". So the REPL session should above would become:

>>> import plotext as plt
>>> plt.xscale("log")
>>> plt.plot(plt.sin(periods=2, length=10**4))
>>> plt.show()
<plot is drawn in the terminal here>
>>> plt.xscale("linear")     # Note this here!
>>> plt.show()
<plot is drawn in the terminal here>
>>> plt.show()
<plot is drawn in the terminal here>
etc...

In a Textual app, this would mean adding (assuming the xscale was the problem here) this at the end of the code to create the plot:

_ = self.plt.build()
self.plt.xscale("linear")

Need more help?

If you need help with this library, or with anything relating to Textual, feel free to come join the Textualize devs on Discord or the other places where we provide support.

Footnotes

  1. Repeated calls to build will happen when the PlottextPlot widget needs to render the plot again, on resize for example. ↩