Logo of the POT toolbox

In this example we plot the logo of the POT toolbox.

This logo is that it is done 100% in Python and generated using matplotlib and plotting the solution of the EMD solver from POT.

# Author: Remi Flamary <remi.flamary@polytechnique.edu>
#
# License: MIT License

# sphinx_gallery_thumbnail_number = 1

import numpy as np
import matplotlib.pyplot as pl
import ot

Data for logo

# Letter P
p1 = np.array([[0, 6.], [0, 5], [0, 4], [0, 3], [0, 2], [0, 1], ])
p2 = np.array([[1.5, 6], [2, 4], [2, 5], [1.5, 3], [0.5, 2], [.5, 1], ])

# Letter O
o1 = np.array([[0, 6.], [-1, 5], [-1.5, 4], [-1.5, 3], [-1, 2], [0, 1], ])
o2 = np.array([[1, 6.], [2, 5], [2.5, 4], [2.5, 3], [2, 2], [1, 1], ])

# Scaling and translation for letter O
o1[:, 0] += 6.4
o2[:, 0] += 6.4
o1[:, 0] *= 0.6
o2[:, 0] *= 0.6

# Letter T
t1 = np.array([[-1, 6.], [-1, 5], [0, 4], [0, 3], [0, 2], [0, 1], ])
t2 = np.array([[1.5, 6.], [1.5, 5], [0.5, 4], [0.5, 3], [0.5, 2], [0.5, 1], ])

# Translating the T
t1[:, 0] += 7.1
t2[:, 0] += 7.1

# Concatenate all letters
x1 = np.concatenate((p1, o1, t1), axis=0)
x2 = np.concatenate((p2, o2, t2), axis=0)

# Horizontal and vertical scaling
sx = 1.0
sy = .5
x1[:, 0] *= sx
x1[:, 1] *= sy
x2[:, 0] *= sx
x2[:, 1] *= sy

Plot the logo (clear background)

# Solve OT problem between the points
M = ot.dist(x1, x2, metric='euclidean')
T = ot.emd([], [], M)

pl.figure(1, (3.5, 1.1))
pl.clf()
# plot the OT plan
for i in range(M.shape[0]):
    for j in range(M.shape[1]):
        if T[i, j] > 1e-8:
            pl.plot([x1[i, 0], x2[j, 0]], [x1[i, 1], x2[j, 1]], color='k', alpha=0.6, linewidth=3, zorder=1)
# plot the samples
pl.plot(x1[:, 0], x1[:, 1], 'o', markerfacecolor='C3', markeredgecolor='k')
pl.plot(x2[:, 0], x2[:, 1], 'o', markerfacecolor='b', markeredgecolor='k')


pl.axis('equal')
pl.axis('off')

# Save logo file
# pl.savefig('logo.svg', dpi=150, transparent=True, bbox_inches='tight')
# pl.savefig('logo.png', dpi=150, transparent=True, bbox_inches='tight')

(-0.43, 9.03, 0.375, 3.125)

Plot the logo (dark background)

pl.figure(2, (3.5, 1.1), facecolor='darkgray')
pl.clf()
# plot the OT plan
for i in range(M.shape[0]):
    for j in range(M.shape[1]):
        if T[i, j] > 1e-8:
            pl.plot([x1[i, 0], x2[j, 0]], [x1[i, 1], x2[j, 1]], color='w', alpha=0.8, linewidth=3, zorder=1)
# plot the samples
pl.plot(x1[:, 0], x1[:, 1], 'o', markerfacecolor='w', markeredgecolor='w')
pl.plot(x2[:, 0], x2[:, 1], 'o', markerfacecolor='w', markeredgecolor='w')

pl.axis('equal')
pl.axis('off')

# Save logo file
# pl.savefig('logo_dark.svg', dpi=150, transparent=True, bbox_inches='tight')
# pl.savefig('logo_dark.png', dpi=150, transparent=True, bbox_inches='tight')

(-0.43, 9.03, 0.375, 3.125)