bary fgw

2 files changed, 172 insertions, 1 deletions

diff --git a/examples/plot_barycenter_fgw.py b/examples/plot_barycenter_fgw.py
new file mode 100644
index 0000000..f416629
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+++ b/examples/plot_barycenter_fgw.py
@@ -0,0 +1,172 @@
+# -*- coding: utf-8 -*-
+"""
+=================================
+Plot graphs' barycenter using FGW
+=================================
+
+This example illustrates the computation barycenter of labeled graphs using FGW
+
+Requires networkx >=2
+
+.. [18] Vayer Titouan, Chapel Laetitia, Flamary R{\'e}mi, Tavenard Romain
+      and Courty Nicolas
+    "Optimal Transport for structured data with application on graphs"
+    International Conference on Machine Learning (ICML). 2019.
+
+"""
+
+# Author: Titouan Vayer <titouan.vayer@irisa.fr>
+#
+# License: MIT License
+
+#%% load libraries
+import numpy as np
+import matplotlib.pyplot as plt
+import networkx as nx
+import math
+from scipy.sparse.csgraph import shortest_path
+import matplotlib.colors as mcol
+from matplotlib import cm
+from ot.gromov import fgw_barycenters
+#%% Graph functions
+
+def find_thresh(C,inf=0.5,sup=3,step=10):
+    """ Trick to find the adequate thresholds from where value of the C matrix are considered close enough to say that nodes are connected
+        Tthe threshold is found by a linesearch between values "inf" and "sup" with "step" thresholds tested. 
+        The optimal threshold is the one which minimizes the reconstruction error between the shortest_path matrix coming from the thresholded adjency matrix 
+        and the original matrix.
+    Parameters
+    ----------
+    C : ndarray, shape (n_nodes,n_nodes)
+            The structure matrix to threshold
+    inf : float
+          The beginning of the linesearch
+    sup : float
+          The end of the linesearch
+    step : integer 
+            Number of thresholds tested        
+    """
+    dist=[]
+    search=np.linspace(inf,sup,step)
+    for thresh in search:
+        Cprime=sp_to_adjency(C,0,thresh)
+        SC=shortest_path(Cprime,method='D')
+        SC[SC==float('inf')]=100
+        dist.append(np.linalg.norm(SC-C))
+    return search[np.argmin(dist)],dist
+
+def sp_to_adjency(C,threshinf=0.2,threshsup=1.8):
+    """ Thresholds the structure matrix in order to compute an adjency matrix. 
+    All values between threshinf and threshsup are considered representing connected nodes and set to 1. Else are set to 0    
+    Parameters
+    ----------
+    C : ndarray, shape (n_nodes,n_nodes)
+        The structure matrix to threshold
+    threshinf : float
+        The minimum value of distance from which the new value is set to 1
+    threshsup : float
+        The maximum value of distance from which the new value is set to 1
+    Returns
+    -------
+    C : ndarray, shape (n_nodes,n_nodes)
+        The threshold matrix. Each element is in {0,1}
+    """
+    H=np.zeros_like(C)
+    np.fill_diagonal(H,np.diagonal(C))
+    C=C-H
+    C=np.minimum(np.maximum(C,threshinf),threshsup)
+    C[C==threshsup]=0
+    C[C!=0]=1   
+    
+    return C 
+
+def build_noisy_circular_graph(N=20,mu=0,sigma=0.3,with_noise=False,structure_noise=False,p=None):
+    """ Create a noisy circular graph
+    """
+    g=nx.Graph()
+    g.add_nodes_from(list(range(N)))
+    for i in range(N):
+        noise=float(np.random.normal(mu,sigma,1))
+        if with_noise:
+            g.add_node(i,attr_name=math.sin((2*i*math.pi/N))+noise)
+        else:
+            g.add_node(i,attr_name=math.sin(2*i*math.pi/N))
+        g.add_edge(i,i+1)
+        if structure_noise:
+            randomint=np.random.randint(0,p)
+            if randomint==0:
+                if i<=N-3:
+                    g.add_edge(i,i+2)
+                if i==N-2:
+                    g.add_edge(i,0)
+                if i==N-1:
+                    g.add_edge(i,1)
+    g.add_edge(N,0)
+    noise=float(np.random.normal(mu,sigma,1))
+    if with_noise:
+        g.add_node(N,attr_name=math.sin((2*N*math.pi/N))+noise)
+    else:
+        g.add_node(N,attr_name=math.sin(2*N*math.pi/N))
+    return g
+
+def graph_colors(nx_graph,vmin=0,vmax=7):
+    cnorm = mcol.Normalize(vmin=vmin,vmax=vmax)
+    cpick = cm.ScalarMappable(norm=cnorm,cmap='viridis')
+    cpick.set_array([])
+    val_map = {}
+    for k,v in nx.get_node_attributes(nx_graph,'attr_name').items():
+        val_map[k]=cpick.to_rgba(v)
+    colors=[]
+    for node in nx_graph.nodes():
+        colors.append(val_map[node])
+    return colors
+    
+#%% create dataset
+# We build a dataset of noisy circular graphs.
+# Noise is added on the structures by random connections and on the features by gaussian noise.
+
+np.random.seed(30)
+X0=[]
+for k in range(9):
+    X0.append(build_noisy_circular_graph(np.random.randint(15,25),with_noise=True,structure_noise=True,p=3))
+    
+#%% Plot dataset
+
+plt.figure(figsize=(8,10))
+for i in range(len(X0)):
+    plt.subplot(3,3,i+1)
+    g=X0[i]
+    pos=nx.kamada_kawai_layout(g)
+    nx.draw(g,pos=pos,node_color = graph_colors(g,vmin=-1,vmax=1),with_labels=False,node_size=100)
+plt.suptitle('Dataset of noisy graphs. Color indicates the label',fontsize=20)
+plt.show()
+
+
+
+#%%
+# We compute the barycenter using FGW. Structure matrices are computed using the shortest_path distance in the graph
+# Features distances are the euclidean distances
+Cs=[shortest_path(nx.adjacency_matrix(x)) for x in X0]
+ps=[np.ones(len(x.nodes()))/len(x.nodes()) for x in X0]
+Ys=[np.array([v for (k,v) in nx.get_node_attributes(x,'attr_name').items()]).reshape(-1,1) for x in X0]
+lambdas=np.array([np.ones(len(Ys))/len(Ys)]).ravel()
+sizebary=15 # we choose a barycenter with 15 nodes
+
+#%%
+
+A,C,log=fgw_barycenters(sizebary,Ys,Cs,ps,lambdas,alpha=0.95)
+
+#%%
+bary=nx.from_numpy_matrix(sp_to_adjency(C,threshinf=0,threshsup=find_thresh(C,sup=100,step=100)[0]))
+for i in range(len(A.ravel())):
+    bary.add_node(i,attr_name=float(A.ravel()[i]))
+ 
+#%%
+pos = nx.kamada_kawai_layout(bary)
+nx.draw(bary,pos=pos,node_color = graph_colors(bary,vmin=-1,vmax=1),with_labels=False)
+plt.suptitle('Barycenter',fontsize=20)
+plt.show()
+
+
+
+
diff --git a/examples/plot_fgw.py b/examples/plot_fgw.py
index 5c2d0e1..bfa7fb4 100644
--- a/examples/plot_fgw.py
+++ b/examples/plot_fgw.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 """
 ==============================