tda-networks/zigzag.py
2018-08-03 17:25:44 +01:00

72 lines
2.1 KiB
Python

import numpy as np
import igraph as ig
import dionysus as d
import pickle
import matplotlib.pyplot as plt
plt.style.use("fivethirtyeight")
plt.rcParams["figure.figsize"] = 10, 6
def sliding_windows(g, res=0.1, overlap=0):
times = np.array(g.es["time"])
duration = res * (times.max() - times.min())
windows = []
for i in range(int(1/res)-1):
edges = g.es.select(time_gt=times.min() + duration*i,
time_lt=times.min() + duration*(i+1))
windows.append(g.subgraph_edges(edges))
return windows
def max_simplicial_complex(g):
return d.Filtration(g.maximal_cliques())
def find_transitions(a):
res = []
prev = False
for i, cur in enumerate(a):
if cur != prev:
res.append(i)
prev = cur
return res
def presence_times(g):
max_simplicial_complex = d.Filtration(g.cliques())
filts = []
for t in np.sort(np.unique(g.es["time"])):
edges = g.es.select(time_eq=t)
cliques = g.subgraph_edges(edges).cliques()
filts.append(d.Filtration(cliques))
presences = [[s in filt for filt in filts] for s in max_simplicial_complex]
presences = [find_transitions(p) for p in presences]
return (max_simplicial_complex, presences)
if __name__ == "__main__":
# Import the data
g = ig.read("data/sociopatterns/infectious/infectious.graphml")
print(g.summary())
# Segment the network into sliding windows (resolution = 5%)
wins = sliding_windows(g, 0.05)
# Compute the presence times of maximal simplices for an example window
print(wins[0].summary())
(f, t) = presence_times(wins[0])
for s in f:
print(s)
print(t)
# Compute the zigzag homology on the window
print("Computing zigzag persistence...")
zz, dgms, cells = d.zigzag_homology_persistence(f, t)
for i, dgm in enumerate(dgms):
print("Dimension: {}".format(i))
for p in dgm:
print(p)
# pickle.dump(dgms, open("diagrams.p", "wb"))
# Plot the persistence diagrams
# for i, dgm in enumerate(dgms):
# d.plot.plot_diagram(dgm, show=False)
# plt.savefig("dgm_{}.png".format(i))