How to plot a chart in the terminal

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?

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.