I often find myself analyzing data in Ruby. Visually representing the data helps one find interesting angles and dig in. However, I was never satisfied with my setup because:
- Existing plotting libraries in Ruby have shortcomings:
- They are not designed to be used in an interactive shell; they either write their output to a file, or if they open a window showing the output it blocks further commands in the shell.
- They have a lot of dependencies.
- Moving data between my Ruby shell (where I am doing the analysis), and another
environment for plotting (e.g. a Python Jupyter notebook with
matplotlib) is cumbersome.
Termplot solves the issues above by having the plots right in the terminal,
and on top of that, provides some other advantages:
- Your workflow is the same whether you are working locally or remotely over SSH.
- You can capture your full data analysis session with the plots using
script.
You might think the fidelity of the terminal is not good enough to make any use of these plots. This hasn't been my experience; using braille characters we get 8 pixels per terminal character, and when doing data analysis I just need something rough to get an idea of what the data is like.
$ gem install termplotrequire 'termplot'
plot = Termplot::Plot.new
x = 0.step(3 * Math::PI, by: 3 * Math::PI / 30).to_a
sin = x.map { |v| Math.sin(v) }
cos = x.map { |v| Math.cos(v) }
plot.add(x, sin)
plot.add(x, cos, 'xg') # The third argument is for style and color, 'x' is to
# draw points not lines, 'g' is for green. This is
# inspired by matplotlib.
plot.drawThis outputs:
While using an interactive shell, you might not want all the boiler-plate. You
can include Termplot::Interactive to import functions directly into the
interactive shell. Here is an example:
> require 'termplot'
> include Termplot::Interactive
> type :dot # By default, Termplot uses braille characters to render, but these
# wouldn't render well in the README, so switch to the dot renderer
# which uses dots, apostrophes, and colons.
> nocolor # Don't render with colors, we can't show the colors in README anyway.
> plot([0, 1], [0, 1])
┌────────────────────────────────────────────────────────────────────────┐
│ ..''│1
│ ...''' │
│ ...'' │
│ ..''' │
│ ...''' │
│ ...'' │
│ ..''' │
│ ...'' │
│ ..''' │
│ ...''' │
│ ...'' │
│ ..''' │
│ ..''' │
│..''' │0
└────────────────────────────────────────────────────────────────────────┘
0 1
> plot([0, 1], [0.5, 0])
┌──────────────────────────────────────────────────────────────────────┐
│''.. │0.5
│ '''... │
│ ''... │
│ ''... │
│ '''.. │
│ '''.. │
│ '''... │
│ ''... │
│ ''... │
│ ''... │
│ '''.. │
│ '''.. │
│ '''... │
│ ''..│0
└──────────────────────────────────────────────────────────────────────┘
0 1
> hold :on
> plot([0, 1], [0, 1])
┌────────────────────────────────────────────────────────────────────────┐
│ ..''│1
│ ...''' │
│ ...'' │
│ ..''' │
│ ...''' │
│ ...'' │
│ ..''' │
│''''''..... ...'' │
│ ''''''..... ..''' │
│ ..:''''...... │
│ ...'' ''''..... │
│ ..''' ''''''..... │
│ ..''' '''''...... │
│..''' '''''...│0
└────────────────────────────────────────────────────────────────────────┘
0 1
> width 30
┌───────────────────────────┐
│ .'│1
│ .' │
│ .' │
│ .' │
│ .' │
│ .' │
│ .' │
│'''.. .'' │
│ ''...' │
│ .'''.. │
│ : '.. │
│ .' ''.. │
│ .' ''.. │
│.' ''.│0
└───────────────────────────┘
0 1
This gem heavily inspired by the
unicode_plot gem.
It follows a similar overall structure, however it:
- Has cleaner more maintainable code.
- Trims some of the functionality (e.g. bar plots).
- Creates a more usable API.
- Adds the
Interactivemodule.