How to plot a chart in the terminal

Question

I'm researching ML/Theano, and recently came across this script: https://gist.github.com/notmatthancock/68d52af2e8cde7fbff1c9225b2790a7f which was cool to play with. And like all ML researchers, I recently upgraded to a server, and while it's more powerful, it also presented me with a problem.

The script is very long, but it ends with this code:

def plot_stuff(inputs, outputs, losses, net_func, n_hidden):
fig,axes = plt.subplots(1,2,figsize=(12,6))

    axes[0].plot(np.arange(losses.shape[0])+1, losses)
    axes[0].set_xlabel('iteration')
    axes[0].set_ylabel('loss')
    axes[0].set_xscale('log')
    axes[0].set_yscale('log')

    x,y = np.mgrid[inputs[:,0].min():inputs[:,0].max():51j, inputs[:,1].min():inputs[:,1].max():51j]
    z = net_func( np.c_[x.flatten(), y.flatten()] ).reshape(x.shape)

    axes[1].contourf(x,y,z, cmap=plt.cm.RdBu, alpha=0.6)
    axes[1].plot(inputs[outputs==0,0], inputs[outputs==0,1], 'or') 
    axes[1].plot(inputs[outputs==1,0], inputs[outputs==1,1], 'sb') 
    axes[1].set_title('Percent missclassified: %0.2f%%' % (((net_func(inputs)>0.5) != outputs.astype(np.bool)).mean()*100))

    fig.suptitle('Shallow net with %d hidden units'%n_hidden)
    plt.show()

if __name__=='__main__':
    n_hidden = 40
    inputs, outputs = gen_data(n_samples_per_class=100)
    losses, net_func = train_neural_network(inputs=inputs, outputs=outputs, n_hidden=n_hidden, n_iters=int(2000), learning_rate=0.1)
    plot_stuff(inputs, outputs, losses, net_func, n_hidden)

Which generates this chart:

And when I tried to run it on the server, which being a sever has no screen only a command line, I predictably got this error:

fedora@ip-173-33-18-911:~/scripting/spiral$ python spiral.py
Iteration 2000 / 2000, Loss: 0.172083
Traceback (most recent call last):
  File "spiral.py", line 133, in <module>
    plot_stuff(inputs, outputs, losses, net_func, n_hidden)
  File "spiral.py", line 110, in plot_stuff
    fig,axes = plt.subplots(1,2,figsize=(12,6))
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 1046, in subplots
    fig = figure(**fig_kw)
  File "/usr/lib/pymodules/python2.7/matplotlib/pyplot.py", line 423, in figure
    **kwargs)
  File "/usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py", line 79, in new_figure_manager
    return new_figure_manager_given_figure(num, figure)
  File "/usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py", line 87, in new_figure_manager_given_figure
    window = Tk.Tk()
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1767, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: no display name and no $DISPLAY environment variable

Is there a way/method/function to display charts and graphs in the command line?

Standstill

No, I don't want to save the graph, I want to display it, just in the terminal. – Standstill

Answer 1

You have a couple of options here:

1. Export to image or PDF. Information found here: http://matplotlib.org/faq/howto_faq.html The key piece of information here is below:

   # do this before importing pylab or pyplot
   import matplotlib
   matplotlib.use('Agg')
   import matplotlib.pyplot as plt
   fig = plt.figure()
   ax = fig.add_subplot(111)
   ax.plot([1,2,3])
   fig.savefig('test.png')
   

2. If your server supports X11 forwarding (or if you can enable/install X11 forwarding), you can SSH into the server by setting your display. From linux, run:

   DISPLAY=:0.0 ssh -Y <server ip>
   

   This will set up your machine to forward any display output from the server to your PC. If you are running Windows, you can use MobaXterm which makes it easy, or configure an X11 client yourself. Mac is similarly easy if I remember correctly.

Guava

There's NO way to display graphs in the terminal? – Standstill

What do you mean display graphs in the terminal? The second way I mention basically does this. It should do exactly what you screenshotted. – Guava

In the actual command line: Like this: imgur.com/mUn6Px1 or this: imgur.com/Skv87Ju – Standstill

I am pretty sure there is no way to do that in matplotlib. I also do not know why you would want to do this. I am assuming you are operating with a server that is not attached to a monitor, and you are SSH'ing into the server to access it. If that is the case, then the second method I mentioned is the standard way of getting output to screen from a more powerful machine. – Guava

@SagnikGhosh it is actually possible (through an unusual requirement), check my answer. – Apeak

Answer 2

termplotlib (a small project of mine) might come in handy here. Install with

pip install termplotlib

and produce terminal plots like

import termplotlib as tpl
import numpy as np

x = np.linspace(0, 2*np.pi, 100)
y = np.sin(x) + x
fig = tpl.figure()
fig.plot(x, y, width=60, height=20)
fig.show()

  7 +---------------------------------------------------+
    |                                                   |
  6 |                                             **    |
    |                                           **      |
    |                                         **        |
  5 |                                       **          |
    |                                     ***           |
  4 |                                  ****             |
    |                              *****                |
  3 |             *****************                     |
    |          ****                                     |
  2 |       ***                                         |
    |     ***                                           |
    |   ***                                             |
  1 |  **                                               |
    |**                                                 |
  0 +---------------------------------------------------+
    0      1       2      3       4      5       6      7

Forging

Good, though, does it really have to rely on gnuplot? Installing it required installing Qt (363 MB) and icu4c (70 MB). This kind of defies the purpose :( – Esther

Anyway to customize the x/y axis? or to make it fixed gap. – Prizewinner

Amazing! Is there any documentation or examples for the package? Or how I can plot several "lines" on the same plot? – Derek

I was having problem to run it after installing with some errors but once I installed gnuplot then it started working. – Atom

Answer 3

Check the package plotext which allows to plot data directly on terminal. It is very intuitive, as its syntax is very similar to matplotlib.

Here is a basic example:

import plotext as plt
y = plt.sin() # sinusoidal signal 
plt.scatter(y)
plt.title("Scatter Plot")
plt.show()

You can also plot bar plots:

and even images:

An example of plotting a continuous data flow is shown here:

It can be installed with

pip install plotext

or with:

pip install "plotext[image]" 

to use plotext with images.

Brookes

It shows strange results even for the simplest chart: x = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10] y = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10] it also fails when there is not tty – Terebinthine

I tried again and It works here. Could you please try it again with the following commands? import plotext.plot as plx; x=list(range(11)); y=list(range(11)); plx.scatter(x,y); plx.show(); – Brookes

You could also first try to uninstall and reinstall plotext with the command: sudo -H pip uninstall plotext; sudo -H pip install plotext. Remember also to use python3. Let me know, thanks. – Brookes

I have updated the package and it works now on Linux, Windows cmd and in Python IDLE. There are also many other changes (like background color and possibility of saving the plot). You can find it at pypi.org/project/plotext. Let me know if it works in your machine. Thanks. – Brookes

It would be nice, However, the axis coordinates are annoying, nobody can keep constantly recalculating e.g. temperature in his head... – Waltman

I understand and I am working on it. Next version will have proper axis. – Brookes

plotext is great, very simple to use, I used it to get a bandwidth reading between my datacenters, have a python iperf3 package running every 30 min and getting bandwidth data, outputs to JSON file then plotext uses that JSON to create a historical chart that shows bandwidth rates via time. I can publish to github if anyone needs the code. – Standin

New version solves all of the errors above :-) – Brookes

Four years later, Plotext is a real gem 💎 – Wellgroomed

Answer 4

You might be interested in checking out uniplot, a Python library which I wrote specifically for ML/data science pipelines. Might be exactly what you are looking for.

Featuring 4x resolution as compared to other terminal plotters, thanks to Unicode.

I doesn't yet do advanced graphics like you have, but for lines, scatter plots and histograms it works just fine.

Servia

nice tool, does what i need it to do. Is it also possible to change color of single plots based on the plot being above or below average/mean? – Wildman

@Wildman Today the color option is boolean, so not directly. What you could do is split the points into above and below average before plotting, and then plot them as if they were two different curves. Alternatively, you are welcome to add an issue with a feature request in the uniplot GitHub repo if you want. – Servia

Answer 5

It is possible to plot raster images in terminals and terminal emulators:

import matplotlib
matplotlib.use('module://matplotlib-sixel')
from pylab import *
plt.plot(sin(arange(100) / 10))
show()

This particular example uses matplotlib-sixel, a library that uses Xterm emulating a Sixel compatible terminal and ImageTrick. Similar technology could be implemented in the Linux terminal (through the Framebuffer) or emulators (kitty or iTerm2). The FOSS community has given great solutions in the last years (like libsixel).

Another option would be using X11 forwarding or using a Sixel-based printer like lsix. But all these options would happens outside the Python shell itself.

Of course, you are probably better off running a Jupyter Notebook in the server than trying to shoehorn an image in a terminal. It is probably not worth it.

Apeak

If you get gui error use : sudo apt-get install python3-tk – Kreis

Here's the module for kitty: matplotlib-backend-kitty – Draught

This is currently not working for me... After installation, matplotlib-sixel reads: "AssertionError". – Dysgraphia

Answer 6

I created a small package called termplot that creates a vertical bar plot from a list.

pip install termplot

import termplot
termplot.plot([1,2,3,4,-5,5,-4,-1,0,-10,-4,-2,3,5,8,10,12,10,8,7,6,5,4,3,2,1])

Atalante

Please add as much information as possible here on SO. Links tend to die over time, so future readers might not benefit from your answer. – Relly

Answer 7

If you want to pop an external window with the chart, run the plot and then

>>> matplotlib.pyplot.show(block=True)

This will pop the chart in a separate window.

If you call plot() several times prior to this call, it will then pop an equal amount of windows with the respective charts. Control returns to Python only when you close all popped chart windows.

I like to wrap it in a little helper function, like so:

def show():
   return matplotlib.pyplot.show(block=True) 

Then I just call show() whenever I want to see any yet unshown plots.

Hadden

Answer 8

It seems to me that terminalplot, which is much more complete than the package suggested by @William234234 might be a good solution.

Example usage:

import terminalplot as tp
import numpy as np
from math import sin, pi

x=np.linspace(0,2*pi,100);
y=[sin(m)+m for m in x];
tp.plot(list(x),y)

Baer

terminalplot's last commit was in 2016. asciiplotlib seems to be more actively maintained – Bondstone

i still give it a +1 as it does has no external dependencies and works out of the box ;) – Fifield