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# -*- coding: utf-8 -*-
"""
===============================
1D Screened optimal transport
===============================
This example illustrates the computation of Screenkhorn:
Screening Sinkhorn Algorithm for Optimal transport.
"""
# Author: Mokhtar Z. Alaya <mokhtarzahdi.alaya@gmail.com>
#
# License: MIT License
import numpy as np
import matplotlib.pylab as pl
import time
import ot.plot
from ot.datasets import make_1D_gauss as gauss
from ot.bregman import screenkhorn
##############################################################################
# Generate data
# -------------
#%% parameters
n = 100 # nb bins
# bin positions
x = np.arange(n, dtype=np.float64)
# Gaussian distributions
a = gauss(n, m=20, s=5) # m= mean, s= std
b = gauss(n, m=60, s=10)
# loss matrix
M = ot.dist(x.reshape((n, 1)), x.reshape((n, 1)))
M /= M.max()
##############################################################################
# Plot distributions and loss matrix
# ----------------------------------
#%% plot the distributions
pl.figure(1, figsize=(6.4, 3))
pl.plot(x, a, 'b', label='Source distribution')
pl.plot(x, b, 'r', label='Target distribution')
pl.legend()
# plot distributions and loss matrix
pl.figure(2, figsize=(5, 5))
ot.plot.plot1D_mat(a, b, M, 'Cost matrix M')
##############################################################################
# Solve Screenkhorn
# -----------------------
# Screenkhorn
lambd = 1e-03 # entropy parameter
ns_budget = 30 # budget number of points to be keeped in the source distribution
nt_budget = 30 # budget number of points to be keeped in the target distribution
tic = time.time()
G_screen = screenkhorn(a, b, M, lambd, ns_budget, nt_budget, uniform=False, restricted=True, verbose=True)
tac_screen = time.time() - tic
# Sinkhorn
tic = time.time()
G_sink = ot.sinkhorn(a, b, M, lambd, verbose=False)
tac_sink = time.time() - tic
pl.figure(4, figsize=(5, 5))
ot.plot.plot1D_mat(a, b, G_screen, 'OT matrix Screenkhorn')
pl.show()
##############################################################################
# Time complexity
# -----------------------
print("Sinkhorn time complexity: %s\n" % tac_sink)
print("Screenkhorn time complexity: %s\n" % tac_screen)
print("Time_Sinkhorn / Time_Screenkhorn: %s\n" % (tac_sink / tac_screen))
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